Saf-T-Liner C2 School Bus Chassis. Owner’s Manual

Foreword

at any time without notice and without incurring obliga-

Introduction

tion. Descriptions and specifications contained in this

This manual provides information needed to operate

publication provide no warranty, expressed or implied,

and understand the school bus chassis and its compo-

and are subject to revisions and editions without notice.

nents. More detailed information is contained in the

Owner’s Warranty Information for North America book-

Environmental Concerns and

let, and in the vehicle’s workshop and maintenance

manuals.

Recommendations

Freightliner chassis are equipped with various chassis

Whenever you see instructions in this manual to discard

and cab components. Not all of the information con-

materials, you should first attempt to reclaim and re-

tained in this manual applies to every vehicle. If parts

cycle them. To preserve our environment, follow appro-

on your chassis differ from those shown, they may have

priate environmental rules and regulations when dispos-

been installed by the vehicle manufacturer; if so, ser-

ing of materials.

vice part responsibility belongs to the vehicle manufac-

turer.

Event Data Recorder

The safety or performance of your vehicle could be ad-

versely affected by the installation of nonstandard com-

This vehicle is equipped with one or more devices that

record specific vehicle data. The type and amount of

ponents. Note the limitations and specifications pro-

vided in the vehicle and chassis manuals, and consult

data recorded varies depending on how the vehicle is

equipped (such as the brand of engine, if an air bag is

your selling dealer before making any alterations to the

vehicle or chassis.

installed, or if the vehicle features a collision avoidance

system, etc.).

For your reference, keep this manual in the vehicle at

all times.

Customer Assistance Center

IMPORTANT: Descriptions and specifications in this

manual were in effect at the time of printing. Freightliner

Having trouble finding service? Call the Customer As-

Custom Chassis Corporation reserves the right to dis-

sistance Center at 1-800-385-4357 or 1-800-FTL-

continue models and to change specifications or design

HELP. Call night or day, weekdays or weekends, for

STI-346 (8/05P)

Printed in U.S.A.

Foreword

dealer referral, vehicle information, or breakdown coor-

1-800-424-9153); go to http://www.safercar.gov; or

dination. Our people are knowledgeable, professional,

write to: Administrator, NHTSA, 400 Seventh

and committed to keeping your vehicle moving.

Street, SW, Washington, DC 20590. You can also

obtain other information about motor vehicle safety

Reporting Safety Defects

from http://www.safercar.gov.

If you believe that your vehicle has a defect which

Canadian customers who wish to report a safety-

could cause a crash or could cause injury or

related defect to Transport Canada, Defect Investi-

death, you should immediately inform the National

gations and Recalls, may telephone the toll-free

Highway Traffic Safety Administration (NHTSA) in

hotline 1-800-333-0510, or contact Transport

addition to notifying Freightliner Custom Chassis

Canada by mail at: Transport Canada, ASFAD,

Corporation.

Place de Ville Tower C, 330 Sparks Street,

Ottawa, Ontario, Canada K1A 0N5.

If the NHTSA receives similar complaints, it may

open an investigation, and if it finds that a safety

For additional road safety information, please visit

defect exists in a group of vehicles, it may order a

the Road Safety website at: http://www.tc.gc.ca/

recall and remedy campaign. However, NHTSA

roadsafety/menu.htm

cannot become involved in individual problems

between you, your dealer, or Freightliner Custom

Chassis Corporation.

To contact NHTSA, you may call the Vehicle

Safety Hotline toll-free at 1-888-327-4236 (TTY:

No part of this publication, in whole or part, may be translated, reproduced, stored in a retrieval system, or transmitted

in any form by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written per-

mission of Freightliner LLC. For additional information, please contact Freightliner LLC, Service Systems and Docu-

mentation, P.O. Box 3849, Portland OR 97208-3849 U.S.A. or refer to http://www.Freightliner.com and http://www.

FreightlinerChassis.com.

Vehicle Identification

Vehicle Specification Label

Vehicle Identification Number

The vehicle specification label lists the vehicle model,

(VIN)

identification number, and major component models. It

The chassis vehicle identification number (VIN) is per-

also recaps the major assemblies and installations

manently attached to the chassis. See Fig. 1.4.

shown on the chassis specification sheet. See Fig. 1.1.

NOTE: Always include the chassis serial number

NOTE: Labels shown in this chapter are examples

(last six digits of the VIN) when communicating

only. Actual specifications may vary from vehicle to

with Freightliner Custom Chassis Corporation.

vehicle.

Federal Motor Vehicle Safety

Standard (FMVSS) Labels

If purchased for service in the U.S., chassis built with-

out a body have a certification label similar to that

shown in Fig. 1.2. In addition, after completion of the

vehicle, a certification label similar to that shown in

Fig. 1.3 must be attached by the final-stage manufac-

turer. This label certifies that the vehicle conforms to all

applicable FMVSS regulations in effect on the date of

completion.

NOTE: On incomplete vehicles, it is the responsi-

bility of the final-stage manufacturer to complete

the vehicle and label it for compliance.

1.1

Vehicle Identification

09/28/98

f080023

Fig. 1.2, Incomplete Vehicle Certification Label, U.S.

1 2

11/21/96

f080053

1. Date of Manufacture: by month and year

2. Gross Vehicle Weight Rating: developed by taking

the sum of all the vehicle’s gross axle ratings

3. Gross Axle Weight Ratings: developed by

considering each component in an axle system—

including suspension, axle, wheels, and tires—and

using the lowest component capacity as the value

for the system

Fig. 1.3, Certification Label, U.S.

09/11/2002

f080123

Fig. 1.1, Vehicle Specification Label

1.2

Driver Controls and Instruments

In the ON position (key turned 45 degrees clockwise),

Instrument and Control Panel

all of the electrical systems are operable. Warning lights

Figure 2.1 represents a typical Freightliner dash

and the buzzer for low air pressure (if equipped with air

equipped with all of the standard and many of the op-

brakes) and low oil pressure operate until the engine is

tional instruments and controls.

started and minimum pressures build up.

A warning and indicator light module, located below the

Panel Light Control Lever

speedometer and tachometer, houses all of the stan-

dard and optional warning and indicator lights. Figure

Turn on the panel lights with the headlight switch. The

2.2 identifies the warning and indicator lights.

panel light lever controls the brightness of the instru-

ment panel lights. Slide the control lever up to brighten

the lights, and down to dim them. Move the control le-

Controls

ver all the way down to turn them off. See Fig. 2.4.

Ignition Switch and Key

Headlight Switch and Daytime

The ignition switch can be turned to four positions: AC-

CESSORY, OFF, ON, and START. See Fig. 2.3.

Running Lights

The key can be inserted and removed only from the

In the down position all lights are off. Move the switch

OFF position. The headlights (low beams only), fog

to the middle position to turn on the parking lights.

lights, turn signals, hazard warning lights, and the park-

Move the switch to the up position to turn on the head-

ing lights operate with the ignition switch in the OFF

lights. See Fig. 2.5.

position, regardless of whether the key is inserted.

For vehicles built to operate in Canada, turn the ignition

In the accessory (ACC) position (key is turned counter-

switch to the ON position and release the parking brake

clockwise), all of the electric gauges operate.

to automatically activate the low-beam headlights (later

model vehicles) at half voltage as daytime running

Turn the key fully clockwise to the START position only

lights. The daytime running lights operate until the park-

when starting the engine. When the engine starts, re-

ing brake is applied, and then will switch off. Turning on

lease the key. When released, the key will rotate coun-

the regular headlights overrides the daytime running

terclockwise to the ON position.

2.1

Driver Controls and Instruments

LOW

OIL

ABS

ENG

DO NOT

TRANS

DOWN

CHK

SHIFT

TEMP

09/12/96

f601174

1. Application Air Pressure Gauge

6. Engine Oil Pressure Gauge

11. Secondary Air Pressure Gauge

2. Air Restriction Gauge

7. Tachometer

12. Warning and Indicator Light

3. Pyrometer

8. Speedometer

Module

4. Voltmeter

9. Fuel Gauge

13. Panel Light Control Lever

5. Water Temperature Gauge

10. Primary Air Pressure Gauge

14. Headlight Switch

Fig. 2.1, Instrument and Control Panel Layout

2.2

Driver Controls and Instruments

LOW

ABS

OIL

ENG

DO NOT

TRANS

DOWN

CHK

SHIFT

TEMP

09/12/96

f601175

1. Low Oil Pressure/High Water

6. Stop Engine Indicator

11. High Oil Temperature Warning

Temperature Warning

7. Engine Check Indicator

(automatic transmission)

2. Low Oil Level Warning

8. Cold-Start Manifold Heater

12. Water in Fuel/Water Separator

3. Alternator Warning Light

Indicator

Warning

4. Brake System Warning

9. Air Cleaner Restriction Indicator

13. Parking Brake Indicator Light

5. ABS Warning Light

10. Do Not Shift Indicator

Fig. 2.2, Warning and Indicator Lights

lights. The vehicle cannot be driven unless either the

Turning the knob counterclockwise decreases the effort

headlights or the daytime running lights are activated.

needed to move the lever.

If the parking brake does not hold the vehicle securely,

Parking Brake Control Lever

depress the brake pedal and release the parking brake.

Turn the knob on the end of the lever clockwise to in-

Vehicles With Hydraulic Brakes

crease the parking brake application.

A parking brake control lever is located to the left of the

steering column. To apply the parking brake, depress

NOTE: Turning the knob clockwise will also in-

the brake pedal, then pull down on the parking brake

crease the effort needed to apply or release the

lever. To release the parking brake, depress the brake

parking brake lever.

pedal and pull the parking brake lever all the way up.

2.3

Driver Controls and Instruments

10/26/94

f600363a

07/10/96

f601179

Fig. 2.4, Panel Light Control Lever

1. Accessory

3. On

2. Off

4. Start

Parking Brake Control Valve

Fig. 2.3, Ignition Switch

Vehicles With Air Brakes

If the parking brake still doesn’t hold the vehicle se-

A diamond-shaped knob to the right of the control panel

curely (after adjustment), check the parking brake lin-

operates the parking brake control valve. When the

ings for the correct thickness, or for contamination. For

knob is pulled out, the vehicle’s spring parking brake is

instructions, see Group 42 of the School Bus Chassis

applied. When the knob is pushed in, the parking brake

Maintenance Manual if equipped with hydraulic brakes.

is released. Before the parking brake can be released,

If equipped with air brakes, see Chapter 8 of this

air pressure in the brake system must be at least 65 psi

manual.

(447 kPa).

See Chapter 7, under the heading "Air Brake System,"

for instructions on how to use the parking brake valve.

2.4

Driver Controls and Instruments

07/09/96

f461080

10/26/94

f600356a

1. Turn Signal Lever

Fig. 2.5, Headlight Switch

2. Hazard Warning Light Tab

Fig. 2.6, Turn Signal/Headlight Dimmer Switch and

Turn Signal Lever

Hazard Warning Tab

The turn signal lever is mounted on the steering col-

ing the tab out. When the hazard warning light tab is

umn. Push the lever counterclockwise to turn on the

pulled out, all of the turn signal lights and both of the

left-turn signal lights; push it clockwise to turn on the

indicator lights on the control panel will flash. To cancel

right-turn signal lights. When one of the signal lights is

the warning lights, move the turn signal lever up or

on, a green indicator light flashes at either the far left or

down, then return the lever to the neutral position. See

far right of the warning and indicator light panel. When

Fig. 2.6.

the turn is completed, the signal will cancel and the le-

ver will return to the neutral position. See Fig. 2.6.

Headlight Dimmer Switch

Hazard Warning Light Tab

Pull the turn signal lever up to change from low-beam

to high-beam headlights, or from high beams back to

The hazard warning light tab is located beneath the turn

low beams. See Fig. 2.6. When the headlights are on

signal lever. Activate the hazard warning lights by pull-

2.5

Driver Controls and Instruments

high beam, a blue indicator light comes on above the

speedometer and tachometer.

NOTE: The ignition switch must be in the ON posi-

tion for the high beams to work.

Allison Automatic Transmission

Controls

Allison automatic transmissions have six shift positions

on the selector lever. See Fig. 2.7. The selector lever is

lighted for night driving. See Chapter 5 for complete

transmission operating instructions.

NOTE: Vehicles equipped with an Arens shift-by-

wire shift control system have an electronic push-

button selector similar to that described below for

MD-series transmissions.

Allison automatic transmission models MD-CR and

07/09/96

f270004

MD-WR are controlled by an electronic control unit

(ECU). The ECU processes information from sensors,

Fig. 2.7, Shift Selector

pressure switches, and the shift selector to automati-

cally control the transmission according to programmed

problem with the transmission system, the lights will go

specifications. See Fig. 2.8.

out. Whenever there is a problem with the transmission

Vehicles with these transmissions have a red do-not-

system, the lights will come on and stay on as long as

shift light in the lens and bezel assembly. Also, there is

the problem exists.

a service light in the indicator panel on the shift selec-

If "service" is displayed in the indicator panel, some fea-

tor. With the ignition switch in the ON position, both

tures may not work, but the vehicle can still be driven. If

lights come on for a few seconds, then if there is no

2.6

Driver Controls and Instruments

troubleshooting procedures. See Chapter 5 for com-

plete transmission operating instructions.

Cruise Control

The cruise control allows you to automatically control

the speed of the vehicle. The switches that operate the

cruise control are located on the instrument panel.

WARNING

Do not use the cruise control system when driving

conditions do not permit maintaining a constant

speed, such as in heavy traffic or on roads that are

winding, icy, snow covered, slippery, or with a loose

driving surface. Failure to follow this precaution

could cause a collision or loss of vehicle control,

10/28/94

f600368a

possibly resulting in personal injury or property

damage.

1. Indicator Panel

2. Mode ID

Fig. 2.8, MD Shift Selector

CAUTION

the do-not-shift light illuminates while driving (accompa-

nied by eight short beeps from the shift selector), oper-

Do not shift to Neutral (N) when using the cruise

control. This will cause the engine to overspeed,

ating limits will be placed on the transmission, such as

restricting upshifts and downshifts. However, the vehicle

which can damage the engine.

can still be driven to reach service assistance. In either

Use the Cruise ON/OFF switch on the instrument panel

situation, have the problem repaired as soon as pos-

to turn the cruise control on or off. Use the

sible. See the Allison Transmission Service Manual for

SET/RESUME switch to select cruise speed or to re-

sume cruise control after slowing down. See Chapter 3.

2.7

Driver Controls and Instruments

High Idle (with cruise control option)

• The green right- and left-turn signal lights, that

flash on and off whenever the outside turn signal

Place the shift lever in Neutral (N). Press the ON/OFF

lights are flashing.

switch on the instrument panel. Accelerate to the de-

sired rpm. Press and release the SET/RESUME switch.

• The blue high-beam indicator light (located above

To disengage high idle, step on the brake pedal or

the speedometer and tachometer), that comes on

move the ON/OFF switch to the OFF position.

when the headlights are on high beam.

• The red parking brake indicator light, that comes

Tilt/Telescope Steering Column

on when the parking brake is applied and the ig-

nition switch is in the ON position. See Fig. 2.9.

(optional)

The optional tilt/telescope steering column is actuated

Standard Warning System

by a control lever on the steering column.

Standard Warning Lights

The optional tilt-only steering column is actuated by ei-

ther a control lever on the steering column or a foot-

Standard red warning lights are for alternator no-

operated control valve located to the left of the clutch or

charge, and the brake system warning. See Fig. 2.9.

brake pedal.

Whenever conditions cause the brake system warning

light to come on, a warning buzzer also alerts the

Electric Horn

driver.

On hydraulic brake systems, the warning light comes on

To sound the electric horn, push the button in the center

and the buzzer sounds when the fluid level is low, or

of the steering wheel.

whenever there is a fluid pressure problem within the

master cylinder.

Warning and Indicator Lights

The oil pressure warning light and buzzer activate

All of the standard and optional warning and indicator

whenever the oil pressure falls below the minimum oil

lights are housed in a lens and bezel assembly, located

pressure recommended by the engine manufacturer.

below the speedometer and tachometer.

See Fig. 2.9.

Standard indicator lights include:

2.8

Driver Controls and Instruments

LOW

ABS

OIL

ENG

DO NOT

TRANS

DOWN

CHK

SHIFT

TEMP

09/12/96

f601176

1. Low Oil Pressure/High Water

6. Stop Engine Indicator

11. High Oil Temperature Warning

Temperature Warning

7. Engine Check Indicator

(automatic transmission)

2. Low Oil Level Warning

8. Cold Start Manifold Heater

12. Water in Fuel/Water Separator

3. Alternator Warning Light

Indicator

Warning

4. Brake System Warning

9. Air Cleaner Restriction Indicator

13. Parking Brake Indicator Light

5. Antilock Braking System (ABS)

10. Do Not Shift Indicator

Warning Light

Fig. 2.9, Warning and Indicator Lights

2.9

Driver Controls and Instruments

See the engine manufacturer’s manual for minimum oil

Optional warning and indicator lights may include: air

pressure levels.

intake warmer, transmission oil temperature, air cleaner

restriction, check engine, and engine shutdown.

The water temperature warning light and buzzer acti-

vate whenever the engine coolant temperature exceeds

When the ignition switch is turned to the ON position,

a preset point determined by the engine manufacturer.

oil and brake system warnings (as equipped) activate

See Fig. 2.9.

until the engine starts and minimum pressures are ex-

ceeded. If the low oil pressure warning light or brake

See the engine manufacturer’s manual for maxi-

system warning light remains on after running the en-

mum water temperature levels.

gine for 15 seconds, shut down the engine and deter-

mine the cause of the problem. See the School Bus

Optional Warning and Indicator Lights

Chassis Workshop Manual for repair procedures.

IMPORTANT: If the warning system does not acti-

CAUTION

vate when the ignition switch is turned to the ON

position, repair the system to provide warning pro-

The vehicle may be programmed for the engine to

tection for oil pressure, coolant temperature, and

derate and eventually shut down if there is a loss of

the brake system.

oil pressure or if coolant temperature becomes too

high. This protects the engine from damage. Under

these conditions, first the check engine light will

Instruments

come on. If the driver continues to drive the vehicle,

the engine derate or shut down light will come on

Tachometer (optional)

and the engine will start to power down or derate.

A tachometer indicates engine speed in revolutions per

Eventually the engine will shut down. Be aware that

minute (rpm), and serves as a guide for shifting the

the vehicle could derate and/or shut down if this

transmission and keeping the engine in the appropriate

option is programmed. Be prepared to park the ve-

rpm range. See Fig. 2.10. For low idle and rated rpm,

hicle in a safe location if it does derate or shut

see the engine identification plate.

down.

The tachometer may include an engine hourmeter. An

engine hourmeter records continuous operating hours of

2.10

Driver Controls and Instruments

10/28/94

f600374a

10/28/94

f600375a

Fig. 2.10, Tachometer

Fig. 2.11, Speedometer

the engine. In cases where actual mileage does not in-

Fig. 2.12. If the temperature remains below 160°F

dicate overall usage, maintenance and lubrication inter-

(71°C) or exceeds a maximum temperature of 210°F

vals for the engine and engine-operated equipment can

(99°C), inspect the cooling system to determine the

be determined by operating hours.

cause. See the School Bus Chassis Workshop Manual

for troubleshooting and repair procedures.

Speedometer

Engine Oil Pressure Gauge

A speedometer registers vehicle speed in both miles

per hour (mph) and kilometers per hour (km/h). Stan-

See the engine manufacturer’s manual for recom-

dard speedometer gauges are equipped with an odom-

mended engine oil pressure gauge readings. See

eter that records total distance traveled in either miles

Fig. 2.13.

or kilometers. See Fig. 2.11.

CAUTION

Water Temperature Gauge

During normal engine operation, the water temperature

A sudden decrease or absence of oil pressure may

gauge should read from 175 to 203°F (79 to 95°C). See

indicate mechanical failure. Bring the vehicle to a

2.11

Driver Controls and Instruments

safe stop and investigate the cause to prevent fur-

ther damage. Do not operate the engine until the

cause has been determined and corrected.

10/28/94

f600377a

Fig. 2.13, Engine Oil Pressure Gauge

10/28/94

f600376a

gine is stopped. A completely discharged battery will

produce only about 12.0 volts. The voltmeter will indi-

Fig. 2.12, Water Temperature Gauge

cate lower voltage as the vehicle is being started or

when electrical devices in the vehicle are being used.

Voltmeter (optional)

If the voltmeter shows an undercharged or overcharged

The voltmeter indicates the vehicle charging system

condition for an extended period, have the charging

voltage when the engine is running and the battery volt-

system and batteries checked at a repair facility.

age when the engine is stopped. See Fig. 2.14. By

NOTE: On a vehicle equipped with a battery isola-

monitoring the voltmeter, the driver can be aware of po-

tor system, the voltmeter measures the average

tential charging system problems and have them re-

voltage of all of the batteries when the engine is

paired before the batteries discharge enough to create

starting difficulties.

running. When the engine is stopped, the voltme-

ter shows only the gel cell battery voltage and

The voltmeter will normally show approximately 13.7 to

does not indicate the voltage of the engine-starting

14.1 volts when the engine is running. The voltage of a

batteries.

fully charged battery is 12.7 to 12.8 volts when the en-

2.12

Driver Controls and Instruments

10/28/94

f600378a

10/28/94

f600380a

Fig. 2.14, Voltmeter

Fig. 2.15, Fuel Gauge

Transmission Oil Temperature Gauge

CAUTION

(optional)

Gel cell batteries can be damaged if the battery

With an Allison automatic transmission, the transmission

voltage is allowed to drop below 12.0 volts or if the

oil temperature gauge reading should not exceed 300°F

charging voltage is more than 14.1 volts. Start the

(149°C) during normal operation. A warning light will

engine to recharge the gel cell before the battery

illuminate to alert the driver if normal operating tem-

becomes fully discharged. If an external charger is

peratures are exceeded.

needed, disconnect the gel cell battery and use only

an external battery charger that has been approved

for gel cell batteries.

CAUTION

Fuel Gauge

A sudden increase in transmission oil temperature

that is not caused by a load increase may indicate

The fuel gauge indicates the amount of fuel in the fuel

mechanical failure. Bring the vehicle to a safe stop,

tank(s). See Fig. 2.15.

2.13

Driver Controls and Instruments

and investigate the cause to prevent further dam-

Maximum Air Restriction in Inches of Water (inH₂O)

age. Do not operate the vehicle until the cause has

At Full Load and At No-Load and

been determined and corrected.

Engine

Governed RPM Governed RPM

Caterpillar

(63 cm)

(30 cm)

Intake-Air Restriction Indicator

Cummins

(63 cm)

(30 cm)

An intake-air restriction indicator measures the vacuum

Mercedes-Benz

(63 cm)

(30 cm)

on the engine side of the air cleaner at the air cleaner

outlet. See Fig. 2.16. If the yellow signal stays locked at

Table 2.1, Maximum Air Restriction in Inches of Water

or above the values shown in Table 2.1 after the engine

(in H₂O)

is shut down, service the air cleaner. Then, press the

NOTE: Rain or snow can wet the filter and cause

yellow button to reset the indicator.

a higher than normal reading temporarily.

Intake-Air Restriction Gauge

The intake-air restriction gauge measures the vacuum

on the engine side of the air cleaner at the air cleaner

outlet. See Fig. 2.17 and Fig. 2.18. Vacuum is mea-

sured in inH₂O (inches/centimeters of water). When the

vacuum reading in normal operation equals the appli-

cable level shown in Table 2.1, the air cleaner needs to

be serviced.

IMPORTANT: Do not rely exclusively on the accu-

racy of the air restriction gauge for filter replace-

ment. The filter must be changed at recommended

01/18/95

f600148a

intervals regardless of what the gauge reads.

Fig. 2.16, Intake-Air Restriction Indicator

NOTE: Rain or snow can wet the filter and cause

a higher than normal reading temporarily.

2.14

Driver Controls and Instruments

05/14/2001

f610552

05/14/2001

f610553

Fig. 2.17, Intake-Air Restriction Gauge (inH₂O)

Fig. 2.18, Intake-Air Restriction Gauge (cm H₂O)

• a set of 18 warning and indicator lights similar to

Instrumentation Control Unit,

those found on a conventional lightbar

Level III

• a 10-key keypad on the auxiliary instrument panel

The level III instrumentation control unit (ICU2M) is an

• a message display screen

advanced programmable electronic dashboard. It can

The message display screen is a 2-line by 20-character

accept information from the sensors and electronic con-

trol units installed on the vehicle and feed it to elec-

vacuum fluorescent display that provides a wide range

of information to the driver.

tronic gauges. Only air gauges operate mechanically.

Some of the information that can be provided by the

There can be up to 14 removable gauges on the driv-

message center includes:

er’s instrument panel (11 electronic, one electrome-

chanical, and two mechanical).

• odometer readings

The Driver Message Center is the heart of the level III

• outside air temperature

ICU. It has three parts:

2.15

Driver Controls and Instruments

• trip information, such as trip miles and hours, idle

The messages this system displays are:

hours, average mph, and leg miles and hours

• "Drive 60 MPH, Gain X MPG"

• fuel information, such as fuel used, miles per gal-

• "Shift to Next Gear, Gain X MPG"

lon, and fuel used idling

• "End Idling, Save X Gal/Hr"

• engine information, such as miles, hours, and

gallons of fuel used

• "Drive Steady Speed, Gain X MPG"

• diagnostic information, such as listings of active

• "Move Throttle Slower, Gain X MPG"

faults and troubleshooting information

In each example, the X value in the statement is vari-

• vehicle information, such as datalink operation

able. The system will estimate and display a numerical

and use data, dash part number, and software

savings gain in place of the X.

number

NOTE: The information provided by the FUEL effi-

Some of the advanced features supported by the level

ciency system is different than, and should not be

III ICU are: Fuel Use Efficiency Level (FUEL) system

confused with, the information available by press-

display, target miles per gallon (MPG), and brightness

ing the FUEL key on the 10-key keypad. The key-

control.

pad and its direct access keys are described in

more detail later in this chapter.

Fuel Use Efficiency Level (FUEL)

If so equipped, the FUEL system continuously monitors

Target MPG

fuel usage efficiency and instantly transmits action mes-

The target MPG feature allows quick and easy checking

sages through the Driver Message Center to help the

of fuel economy through the "MPG Graph/Target MP-

driver get better mileage. The system may suggest a

G..Odometer" screen. See Fig. 2.19.

different speed, gear, or throttle position, and will calcu-

late and transmit estimated fuel savings based on the

NOTE: Use the LEFT ARROW key to lower the

suggested action. It also calculates and displays a bar

target MPG, and the RIGHT ARROW key to raise

graph that shows a fuel efficiency score as a percent-

it. For more information on how to set target MPG,

age of optimum efficiency.

2.16

Driver Controls and Instruments

Brightness Control

The panel light dimmer switch normally controls the

−

0%II

brightness of all panel and gauge lights, including the

level III ICU message display screen. With the parking

12.3MPG

9012.0MI R

brake set, the ICU keypad can control the brightness of

the message display screen independently of the other

10/31/2000

f601412b

lights. If the panel lights are set to maximum brightness,

the message display screen cannot be brightened any

Fig. 2.19, MPG Graph/Target MPG.Odometer Screen

further.

adjust screen display brightness, change lan-

NOTE: Use the LEFT ARROW key to dim the

guages or switch between US and metric units of

message display screen, and the RIGHT ARROW

measure, see "Setup Information" later in this

key to brighten it. For more information on how to

chapter.

set the brightness of the message display screen,

The "Target MPG" area is on the second line of the dis-

see "Setup Information" later in this chapter.

play, to the left of the odometer. It shows the actual tar-

When the parking brake is released, the arrow keys no

get miles per gallon (MPG).

longer work to change the brightness of the message

Example: A reading of "12.3 MPG" indicates that the

display screen, but the settings stay in effect unless the

target MPG is 12.3 miles per gallon.

headlights are turned on. With the headlights on, the

message display screen dims slightly to adjust to night-

The "MPG Graph" on the first line of the display gives

time conditions.

the same information in dynamic form. The "0%" mark

in the center of the line gives the target MPG. Bars

Warning and Indicator Lights

showing to the right of the display indicate that short

term fuel economy is above the target; bars showing to

There can be up to 18 warning and indicator lights in-

the left of the display indicate that short term fuel

stalled in the level III ICU. See Fig. 2.20.

economy is below the target.

2.17

Driver Controls and Instruments

• The green right- and left-turn signal lights flash

•

The blue high-beam indicator light comes on

on and off whenever the outside turn signal lights

when the headlights are on high beam.

are flashing.

•

The yellow "Check Engine" (CHK ENG) light

comes on to indicate an engine condition such as

low coolant level, high coolant temperature, or

low oil pressure. It also comes on when a fault is

detected or recorded.

FASTEN SEATBELTS

•

The red "Engine Protection" (ENG PROT) light

0000432 MILES

comes on to warn that the protection system

available on the engine has been activated.

•

Installed on Cummins engines only, the red "Stop

Engine" (STOP ENG) light comes on to warn that

08/28/2002

f600996d

the engine is not functioning normally. Pull the

vehicle over to the side of the road and shut

Typical installation shown. Location and function of

down the engine immediately.

optional lights may vary.

1. Left-Turn Indicator

•

The red low air pressure (LOW AIR) warning light

2. Engine Protection Warning Lamp Indicator

and buzzer come on whenever air pressure in the

3. Check Engine Indicator

primary or secondary air reservoir falls below 64

4. Stop Engine Warning

to 76 psi (440 to 525 kPa).

5. Optional Indicator

6. Message Display Screen

•

Depending on options installed, other warning

7. High-Beam Indicator

and indicator lights can be installed in the spaces

8. Low Air Warning

marked "OPT." Available optional indicator lights

9. Right-Turn Indicator

include: air bag warning, alternator no charge

10. Air Bag Warning (optional)

warning, automatic transmission overheat warn-

11. ABS Warning

ing, trailer ABS warning, ECAS (electronic sus-

12. Wheel Spin Indicator

pension) transfer indicator, and ECAS failure

warning.

Fig. 2.20, Driver Message Center, Level III ICU

2.18

Driver Controls and Instruments

NOTE: The functions of the ABS warning light are

• Set the brightness of the message display screen

explained under "Meritor WABCO Antilock Braking

independently of the panel dimmer switch. Use

the LEFT ARROW key to dim the display and the

System (ABS)" in Chapter 7.

RIGHT ARROW key to brighten it.

Keypad

• Record significant data using the EVENT key

(optional—if a data logging unit is installed).

The level III ICU is controlled by a keypad located on

the auxiliary dash panel. See Fig. 2.21. This keypad,

NOTE: One key is blank and is not usable at this

which has 10 keys, can be used to:

time.

• Call up information onto direct access screens.

Level III ICU Ignition Sequence

• Move about from screen to screen while the ve-

hicle is stationary.

If the headlights are turned on, the screen displays the

odometer and waits for the ignition switch to be turned

• Set up the display.

to the ON position.

When the ignition switch is first turned to the ON posi-

tion, all of the electronic gauges complete a full sweep

of their dials, the warning and indicator lights light up for

five seconds, and the buzzer sounds for two seconds.

See Fig. 2.22.

Dedicated Keys

General Keys Control Keys

NOTE: The air gauges and voltmeter do not

08/08/96

f601009

sweep.

Fig. 2.21, 10-Key Keypad

Once the ignition switch has been turned to the ON po-

sition, the screen displays the "Freightliner" message. At

• Set a target MPG to monitor fuel economy while

the same time, the level III ICU conducts a roll call of all

driving. Press the LEFT ARROW key to lower the

of the electronic control units (ECUs) installed on the

target MPG and the RIGHT ARROW key to raise

vehicle, looking for active faults.

it.

2.19

Driver Controls and Instruments

If there are no active faults, the screen displays the

"Fasten Seat Belts/Odometer" screen.

If, however, the level III ICU has received active fault

codes or an electronic control unit (ECU) fails to re-

spond to the roll call, it shows the "Active Faults" screen

and displays the number of active faults up to a total of

eight. If desired, press RIGHT ARROW to see the ac-

tive fault codes. See Fig. 2.19. Continuing to press the

right arrow key will display all additional fault codes (if

any).

To go on, press LEFT ARROW, or if the engine is run-

ning, release the parking brake to go on to the "Fasten

Seat Belts/Odometer" screen.

Unless the engine is running, the ignition sequence

07/29/97

f601415

ends with the "Fasten Seat Belts/Odometer" screen.

Fig. 2.23, Level III ICU at the End of the Ignition

IMPORTANT: At this point, if the vehicle has a

Sequence

communications system and an incoming mes-

sage is available, it will be displayed. To dismiss

The Message Display Screen

the incoming message, press any key on the key-

To understand the information displayed on the mes-

pad.

sage display screen, here is an example of screen lay-

With the engine idling (the vehicle not moving), the igni-

out. On the "Idle Hours/Idle Gallons..Odometer" screen,

tion sequence cycles on, and displays the "Idle Hours/

idle hours are displayed on the top line with the words

Idle Gallons..Odometer" screen. See Fig. 2.23.

"Idle Hours" on the left side of the screen and the num-

ber of hours on the right. On the bottom line, the num-

ber of idle gallons is on the left and the odometer miles

are on the right, with a space in between. See

Fig. 2.24.

2.21

Driver Controls and Instruments

NOTE: Press the LEFT ARROW key to lower the

target MPG and the RIGHT ARROW key to raise

it. For more information on how to set the target

MPG, see "Setup Information" later in this chapter.

Level III ICU Roll Call

Each time that the ignition switch is turned to the ON

position, the level III ICU roll call function requests data

from each ECU on the databus. If the ECU does re-

spond to this request, the databus is communicating

with that ECU and no fault code is displayed.

NOTE: Each ICU is configured to receive re-

sponses from a list of selected ECUs as installed

on that particular vehicle.

If the ECU does not respond to this request, the level III

ICU displays an active fault code that indicates that the

07/29/97

f601411

databus is not communicating with that ECU. For a

sample fault code and message of this type, see

Fig. 2.24, Idle Hours/Idle Gallons..Odometer Screen

Fig. 2.25.

Once the parking brake is released (whether the vehicle

Level III ICU Odometer

is moving or not), the regular message screen display is

the "MPG Graph/Target MPG..Odometer" screen. The

The level III ICU odometer is a seven-digit display with

MPG graph is a dynamic display graph demonstrating

one decimal point after the sixth digit allowing it to dis-

how the actions of the driver affect fuel economy. The

play tenths of miles (or kilometers).

graph moves to the right as fuel economy improves.

When first installed, the odometer starts at 0.0 miles (or

See Fig. 2.19.

kilometers). When replaced, the odometer does not

2.22

Driver Controls and Instruments

Alert Screens

Alert screens appear whenever a condition requiring an

alert occurs. They appear when the vehicle is moving;

they override the regular screen display. They are warn-

ings, cautions, or other messages that require the driv-

er’s attention, but not all of them are critical to the op-

eration of the vehicle. Warning messages always

display at full brightness.

More important messages take priority over less impor-

tant messages. The order of importance, or priority, is:

1. Eaton VORAD Warnings (if so equipped)

2. Parking Brake On (with the vehicle moving)

3. Low Oil Pressure, High Coolant Temperature, Low

Coolant Level, and Low Voltage

4. Alternate Speedometer

07/29/97

f601413

5. Recirc Mode Engaged, and Provide Fresh Air

6. Low Fuel Level

Fig. 2.25, Level III ICU Roll Call Fault Code and

Message

7. Turn Signal On

start with the engine miles but starts again from 0.0 and

8. Service Warnings

cannot be changed up or down.

9. No Datalink Activity

IMPORTANT: Although the odometer uses data

"Parking Brake On" Screen

supplied by the engine ECM to update its count, it

keeps its own mileage starting from the zero point,

This warning message and alarm tone come on when-

which marks where it was first installed.

ever the parking brake is applied and the vehicle is

2.23

Driver Controls and Instruments

moving faster than 2.5 miles per hour or the clutch has

NOTE: If there is more than one alert message to

been depressed. The word "Warning" flashes on the

display, pressing any key takes you to the next

message display screen above the message "Parking

message, and so on until all of the messages

Brake On." The screen and alarm tone go away only

have been received.

when the parking brake is released. See Fig. 2.26.

If low oil pressure is detected during the ignition se-

quence, it displays as an active fault and the alert

screen does not appear.

After 30 seconds, this message displays again and can

be dismissed as before by pressing any key.

"Low Coolant Level" Screen

07/29/97

f601414

This warning message and alarm tone activate when-

ever the coolant level falls below a preset point. The

Fig. 2.26, Parking Brake On Screen

word "Warning" flashes on the message display screen

above the message "Low Coolant Level."

The "Parking Brake On" screen overrides any other

screen message.

This message follows the same rules of dismissal and

display as "Low Oil Pressure."

"Low Oil Pressure" Screen

"High Coolant Temp" Screen

This warning message and alarm tone come on when-

ever the oil pressure falls below the minimum oil pres-

This message and alarm tone come on whenever the

sure specified by the engine manufacturer, whether the

engine coolant temperature exceeds a preset point

vehicle is idling or in motion. The word "Warning"

specified by the engine manufacturer (see the engine

flashes on the message display screen above the mes-

manual for this temperature). The word "Warning"

sage "Low Oil Pressure." To dismiss the message,

flashes on the message display screen above the mes-

press any key on the keypad.

sage "High Coolant Temp."

This message follows the same rules of dismissal and

display as "Low Oil Pressure."

2.24

Driver Controls and Instruments

"Low Voltage" Screen

seconds every 254 seconds (about every four minutes)

until the driver switches to fresh air, either by selecting

On some vehicles, this message and alarm tone come

fresh air on the fresh/air recirculation switch or by rotat-

on whenever a low voltage condition is detected by the

ing the air circulation switch away from maximum air

instrumentation control unit. The word "Warning" flashes

conditioning and to one of the other positions.

on the message display screen above the message

"Low Voltage."

"Low Fuel Level" Screen

This message follows the same rules of dismissal and

Fuel level is continuously monitored by the ICU. When

display as "Low Oil Pressure."

the fuel level drops to 1/8th full the word "Warning"

flashes on the message display screen above the mes-

"Faulty Speedo Gauge" Screen

sage "Low Fuel Level."

This message is displayed when the system detects a

faulty speedometer. This becomes the default screen,

"Turn Signal On" Screen

and vehicle speed is displayed as a digital readout at

This warning message (the alarm tone is optional)

the bottom left of the screen. All other screens and

comes on whenever the turn signal remains on beyond

functions operate normally.

a preset time or distance traveled. The word "Warning"

flashes on the display screen above the message "Turn

"Recirc Mode Engaged" and "Provide Fresh

Signal On."

Air" Screens

To dismiss this message, either turn off the turn signal

The "Recirc Mode Engaged" screen comes on when-

or press any key on the keypad.

ever recirculated air is selected on the fresh/air recircu-

lation switch or the air circulation switch is rotated to the

Service Warnings

maximum air conditioning position. It displays one time

Service warning screens display during the ignition se-

only for seven seconds. It notifies the driver that recir-

quence and indicate that a service interval has been

culated air is being used and that fresh air needs to be

reached or exceeded, and that maintenance is required.

provided after 20 minutes.

The messages may indicate the number of miles or

If fresh air is not provided after 20 minutes, the "Provide

hours until the next service, or, once passed, the num-

Fresh Air" message is displayed. It displays for seven

ber of miles or hours ago that maintenance should have

2.25

Driver Controls and Instruments

been performed. The messages read "X Miles To Next

Data for each of the above screens can be reset

Service," "X Hours To Next Service," "Service Was Due

(cleared). To reset, display the screen and push the Set/

X Mi Ago," and "Service Was Due X Hr Ago." The letter

Reset key twice within six seconds (a confirmation

X represents the number of miles or hours pro-

screen will display after you press the key once).

grammed. The ICU2M can be programmed using Ser-

NOTE: Resetting "Trip Miles and Hours" also re-

viceLink to generate service warnings in either miles or

hours, but not both.

sets "Leg Miles and Hours."

Press the TEMP key to display the outside air tempera-

"No Datalink Activity" Screen

ture.

The "No Datalink Activity" screen comes on whenever

If the vehicle has a data logging unit, press the EVENT

the datalink is not receiving data.

key to record data about a significant driving event (en-

gine problem, driving problem, unusual vehicle opera-

If the condition persists, take the vehicle in for service

as soon as possible to discover the cause of the prob-

tion, etc.). Normally, the screen displays "Data Being

Recorded."

lem.

NOTE: If the memory in the data logger is full, the

Direct Access Screens

screen instead displays "Memory Full/Data Not

The driver can also override the regular screen display

Recorded." If the data logger is not connected or

at any time by pressing the keypad to display one of

not responding, the screen displays "Data

the direct access screens.

Recorder/Not Responding." If the EVENT key was

pressed recently (within the last two minutes), the

• Press the TRIP key for the "Trip Miles and Trip

screen displays "Still Recording/Last Event."

Hours" screen.

• Press the FUEL key for the "Fuel Used and Aver-

Stationary Access Screens—Used

age MPG" screen.

With Parking Brake Applied

• Press the LEG key for the "Leg Miles and Leg

Hours" screen.

The stationary access screens are a series of informa-

tional displays that give trip, fuel, engine, diagnostic,

setup, and vehicle information.

2.26

Driver Controls and Instruments

For reasons of safety, stationary access screens can be

NOTE: Resetting "Trip Miles and Hours" also re-

seen only when the vehicle is not moving and the park-

sets "Leg Miles and Hours."

ing brake is applied.

Fuel Information

Each set of stationary access screens has a title screen

followed by one or more data screens. To move forward

Fuel information provides two data screens: "Fuel Used

and backward through these screens, use the three ar-

and Average MPG" and "Idle Gallons and PTO Gal-

row keys as shown in Fig. 2.27, Fig. 2.28, and

lons." See Fig. 2.27.

Fig. 2.29.

"Fuel Used and Average MPG" displays the gallons of

fuel used since the last reset. At the start of a trip, after

Trip Information

refueling, or whenever desired, press RESET (SET/

Trip information provides three data screens: "Trip Miles

RESET twice) to set fuel used and average miles per

and Hours," "Idle Hours and Average MPH," and "Leg

gallon back to zero.

Miles and Hours." See Fig. 2.27.

NOTE: Resetting "Trip Miles and Hours" does not

"Trip Miles and Hours" displays the number of miles

also reset "Fuel Used and Average MPG" or "Idle

and hours driven since the start of the trip. At the start

Gallons and PTO Gallons." Fuel Information must

of a trip, press RESET (SET/RESET twice) to set trip

be reset separately.

miles and hours back to zero.

"Idle Gallons and PTO Gallons" displays the gallons of

NOTE: Resetting "Trip Miles and Hours" also re-

fuel used idling and to operate the Power Take Off unit

sets "Idle Hours and Average MPH."

(if installed). At the start of a trip or whenever desired,

"Idle Hours and Average MPH" displays the hours spent

press RESET to set idle gallons and PTO gallons back

idling and the average miles per hour.

to zero.

"Leg Miles and Hours" records the number of miles and

Engine Information

hours driven since the start of the leg. At the start of a

new leg, press RESET to set leg miles and hours back

Engine information provides two data screens: "Engine

to zero.

Miles and Hours," and "Engine Gallons and PTO Gal-

lons." See Fig. 2.27 or Fig. 2.28.

2.27

Driver Controls and Instruments

IDLE HOURS 1234:56

12.3 GAL 1234567 MI

FASTEN SEATBELTS

1234567 MILES

IGNITION

ON ONLY

IDLING

TRIP

TRIP MILES 123456.7

IDLE HOURS 1234:56

LEG MILES 123456.7

INFORMATION

TRIP HOURS 1234:56

AVERAGE MPH 12.3

LEG HOURS 1234:56

FUEL

FUEL USED 12345.6

IDLE GALLONS 12345.6

INFORMATION

AVERAGE MPG 12.34

PTO GALLONS 12345.6

ENGINE

ENG MILES 1234567.8

ENG GALLONS 123456.7

INFORMATION

ENG HOURS 123456:78

PTO GALLONS 123456.7

=RESET (PUSH RESET/SET KEY TWICE)

=SET (PUSH RESET/SET KEY ONCE)

01/28/98

See applicable figure

f040324a

Fig. 2.27, Trip Information, Fuel Information, and Engine Information

2.28

Driver Controls and Instruments

IDLE HOURS 1234.56

12.3 GAL 1234567 MI

FASTEN SEATBELTS

1234567 MILES

See applicable Figure for trip and fuel information.

IGNITION

ON ONLY

ENGINE

ENG MILES 1234567.8

ENG GALLONS 123456.7

IDLING

INFORMATION

ENG HOURS 123456:78

PTO GALLONS 123456.7

For each fault, display fault codes and description.

DIAGNOSTIC

ACTIVE FAULTS

FIRST

SECOND

LAST

INFORMATION

1234 or NONE

For each fault, display fault codes and description.

123 HIST DASH FAULTS

PUSH RESET TO

FIRST

LAST

LAST CLEAR 1234567

CLEAR DASH FAULTS

LAST OCCR

FIRST OCCR

=RESET (PUSH RESET/SET KEY TWICE)

02/13/96

See applicable Figure.

=SET (PUSH RESET/SET KEY ONCE)

f040325

Fig. 2.28, Engine Information and Diagnostic Information

2.29

Driver Controls and Instruments

See

applicable

SETUP

PUSH SET KEY TO

TARGET MPG 7.0

INFORMATION

CHANGE TARGET MPG

<−−LESS MORE−−>

Figure.

PUSH SET KEY TO

DISPLAY BRIGHTNESS

CHANGE BRIGHTNESS

<−−LIGHT DARK−−>

CURRENT LANGUAGE

IS FLASHING

PUSH SET KEY TO

LANGUAGE ENGLISH

CHANGE LANGUAGE

FRENCH SPANISH

CURRENT UNITS

IS FLASHING

PUSH SET KEY TO

UNITS

ENGLISH METRIC

CHANGE UNITS

VEHICLE

DATA LINK ACTIVE

DATA LINK STATUS

DASH # A06−XXXXX−XXX

INFORMATION

USAGE 40% ERROR 6%

SW#

7.3.9

=RESET (PUSH RESET/SET KEY TWICE)

To trip information

=SET (PUSH RESET/SET KEY ONCE)

01/29/98

See applicable Figure.

f040326a

Fig. 2.29, Setup Information and Vehicle Information

2.30

Driver Controls and Instruments

"Engine Miles and Hours" displays the total miles and

When prompted by the screen, press SET (push the

hours logged by the engine since installation.

SET/RESET key once). The units that are setable will

be blinking. Use the arrow keys (LEFT, RIGHT, and

NOTE: Engine information is supplied by the en-

DOWN) until the display shows the desired setup.

gine Electronic Control Module (ECM). It can be

Press SET again when finished to save the new set-

reset using engine diagnostic tools. For more in-

tings. See Fig. 2.29.

formation, see the engine manufacturer’s manuals.

Vehicle Information

"Engine Gallons and PTO Gallons" displays the gallons

of fuel used by the engine and PTO since installation.

Vehicle information displays important information, in-

cluding datalink activity and status, ICU part number,

Diagnostic Information

and software identification number.

Diagnostic information provides two sets of data

The "Datalink Active" screen is a dynamic display that

screens: "Active Faults," followed by a separate screen

shows if the datalink unit is active at the given time. If

for each fault until all have been shown, and "Historical

all of the arrows are pointing down, the level III ICU has

Dash Faults," also followed by a separate screen for

not received any information on the datalink since the

each fault until all have been shown. See Fig. 2.28.

last time that the ignition switch was turned to the ON

position.

"Active Faults" cannot be reset. Active faults can be

cleared only by correcting the fault.

The "Datalink Status" screen is also dynamic, showing

current datalink use and error rate. The other screen,

"Historical Dash Faults" displays all dash faults since

which shows the ICU part number and the software

the last reset. The second line of the display shows the

identification number, is informational only. See

mileage the last time faults were cleared.

Fig. 2.29.

Setup Information

After vehicle information, pressing the DOWN ARROW

takes you back to trip information and so on.

Setup information allows the user to change the target

MPG, the brightness of the screen display, the language

of the display (English, French, or Spanish), and the

units of measurement (English/US conventional or met-

ric).

2.31

Driver Controls and Instruments

Hood Tilting

A grab handle at the front of the hood provides a hand-

hold for hood tilting. Stop cables prevent the hood from

overtravel. In the operating position, the hood is se-

cured to the lower cab half-fenders by a hold-down

latch on each side of the hood.

To Tilt the Hood:

1. Apply the parking brake.

2. Release both hood hold-down latches by pulling the

ends up. See Fig. 2.30.

3. Using the bumper step and grab handle, slowly tilt

the hood until the stop cables support it. See

10/01/93

f720073

Fig. 2.31.

Fig. 2.30, Unlatch the Hood

CAUTION

2. As the hood goes over center, use the bumper step

and grab handle to control the rate of descent to

Do not let the hood free fall to the full-open posi-

the operating position.

tion. To do so could cause damage to the hood or

3. Make sure that the hood is flush with the cowl, then

hood straps.

secure the hood by engaging both hood hold-down

latches.

To Return the Hood to the Operating

IMPORTANT: Make sure that both hold-down

Position:

latches are fully engaged before operating the ve-

1. Grasp the grab handle, and lift the hood to the 45-

hicle.

degree position.

2.32

Engines

engage, which could cause ring gear and starter

Engine Starting

pinion damage.

NOTE: Before starting the engine, read Chapter 2

Moving a vehicle with the starter and/or using the

for detailed information on how to read the instru-

starter to bump the engine for maintenance proce-

ments and operate the controls.

dures is strictly prohibited. Use of these methods to

Whenever you start an engine, watch for any signs of

bump the engine over or move the vehicle can

engine problems. If the engine vibrates, misfires, or

cause the pinion to release and re-engage, which

makes unusual noises, shut down the engine as soon

could cause ring gear and starter pinion damage.

as possible and determine the cause of the problem.

IMPORTANT: Ring gear and starter pinion damage

Frequently, engine damage may be avoided by a quick

caused by improper starting procedures is not

response to early indications of problems.

warrantable.

CAUTION

Pre-Start

When starting a vehicle equipped with a manual

NOTE: These pre-start steps apply to all engines.

transmission and clutch lock out switch, the clutch

1. Perform the engine pretrip inspection and daily

pedal must be fully depressed during the entire

maintenance checks in Chapter 8.

start sequence. Failure to do so can cause the pin-

ion to release and re-engage, which could cause

2. Set the parking brake.

ring gear and starter pinion damage.

3. For manual transmissions, place the transmission in

If a vehicle does not start on the first attempt, make

Neutral (N) and disengage the clutch.

sure that the engine has completely stopped rotat-

For automatic transmissions, make sure that the

ing before reapplying the starter switch. Failure to

transmission shift control is in Neutral (N) or Park

do so can cause the pinion to release and re-

(P).

NOTE: On vehicles equipped with a neutral start

switch, the transmission must be in Neutral (N)

3.1

Engines

before the engine can be started. For air start sys-

CAUTION

tems, check the air supply before starting the en-

gine. There must be at least 100 psi (689 kPa) of

Protect the turbocharger during the start-up by not

air pressure available.

opening the throttle or accelerating the engine

above 1000 rpm until normal engine idle oil pres-

Starting Precautions, All Engines

sure registers on the gauge.

WARNING

Caterpillar

NOTE: Before attempting to start the engine, fol-

Do not use any starting aid, such as ether, in en-

gines with an intake air preheater. This could cause

low the steps in "Pre-Start."

an explosion, resulting in serious personal injury or

1. Turn the ignition switch to the ON position. See

death.

Fig. 3.1. The CHECK ENGINE indicator comes on

for five seconds.

CAUTION

IMPORTANT: The INTAKE HEATER indicator

stays on for a minimum of two seconds, regard-

Don’t crank the engine for more than 30 seconds at

less of coolant temperature. Wait until the INTAKE

a time during any of the following procedures. Wait

HEATER indicator goes out before attempting to

two minutes after each try to allow the starter to

cool. Failure to do so could cause starter damage.

start the engine.

2. Turn the ignition switch to the START position. Re-

NOTE: Some starters are equipped with optional

lease the switch the moment the engine starts.

overcrank protection. If overcranking occurs, a

thermostat breaks the electrical circuit to the

2.1

If the engine does not start after 15 to 20

starter motor until the motor has cooled.

seconds of cranking, turn the ignition switch

to the OFF position.

3.2

Engines

CAUTION

If the oil pressure is too low, shut down the engine

immediately to prevent serious damage. If the ve-

hicle is equipped with an automatic shutdown sys-

tem, the engine will shut down after 30 seconds.

3. The engine may be operated at low load and speed

once engine oil pressure has reached 10 psi (69

kPa) and air pressure (if applicable) has reached

64 to 76 psi (441 to 524 kPa).

IMPORTANT: If the engine is operated at low load,

it will reach normal operating temperature sooner

07/10/96

f601179

than at idle speed. Limit unnecessary idle time to

1. Accessory

3. On

10 minutes or less.

2. Off

4. Start

4. When the engine has reached the minimum operat-

Fig. 3.1, Ignition Switch Positions

ing temperature of 160°F (71°C), the engine may

be operated at full load.

2.2

Wait two minutes to allow the starter motor

to cool. Turn the ignition switch back to the

Cummins

ON position and try to start the engine

again.

CAUTION

2.3

As soon as the engine starts, release the

ignition switch allowing the engine to run at

Never attempt to start any Cummins IS series elec-

a slow idle.

tronic engine (ISB, ISC, ISL) using ether or any

other starting fluid. Serious engine damage could

result.

3.3

Engines

NOTE: Before attempting to start the engine, fol-

CAUTION

low the steps in "Pre-Start."

1. Turn the ignition switch to the ON position. See

Protect the turbocharger during the start-up by not

Fig. 3.1. The CHECK ENGINE indicator comes on

opening the throttle or accelerating the engine

for five seconds. Leave the ignition switch in the

above 1000 rpm until normal engine idle oil pres-

ON position until the CHECK ENGINE indicator

sure registers on the gauge.

goes out.

5. Idle the engine for three to five minutes at 1000

IMPORTANT: The INTAKE HEATER indicator

rpm before operating the engine under load.

stays on for a minimum of two seconds, regard-

less of coolant temperature. Wait until the INTAKE

Mercedes-Benz

HEATER indicator goes out before attempting to

NOTE: Before attempting to start the engine, fol-

start the engine.

low the steps in "Pre-Start."

2. Turn the ignition switch to the START position. After

the engine starts, release the key.

CAUTION

3. Bring the engine up to operating speed gradually as

it warms up and develops stable oil pressure.

Never attempt to start any Mercedes-Benz elec-

tronic engine using ether or any other starting fluid.

NOTE: When the engine is started, it takes a short

Serious engine damage could result.

time to build up a lubricating oil film between the

shafts and bearings, and between the pistons and

1. Turn the ignition switch to the ON position. See

cylinder walls. The oil pressure gauge indicates

Fig. 3.1. All of the electronic gauges on the ICU

any drop in lubricating oil pressure within 15 sec-

(instrumentation control unit) complete a full sweep

of their dials, the warning and indicator lights light

onds of engine start-up.

up, and the buzzer sounds for three seconds.

4. If minimum engine oil pressure at idle of 10 psi (69

kPa) does not register within 15 seconds, shut

IMPORTANT: The INTAKE HEATER indicator

down the engine.

stays on for a minimum of two seconds, regard-

less of coolant temperature. Wait until the INTAKE

3.4

Engines

HEATER indicator goes out before attempting to

an explosion, resulting in serious personal injury or

start the engine.

death.

2. Turn the ignition switch to the START position.

Modern electronic engines do not normally require spe-

Without touching the throttle pedal, start the engine.

cial starting aids. At low temperatures, intake air pre-

heaters, manifold preheaters, oil pan heaters, fuel heat-

3. Idle the engine for one to three minutes at 700 rpm

ers, or water jacket heaters are sometimes used to

(600 rpm for 6-cylinder engines) before operating

assist in starting.

the engine under load.

If the engine does not start, prime the fuel system. For

4. Check the oil pressure gauge for any drop in lubri-

instructions, see the engine manufacturer’s Operation

cating oil pressure or mechanical malfunction in the

and Maintenance Manual.

lubricating oil system. Minimum oil pressure at idle

is 7 psi (50 kPa).

In cold weather, use winter-grade (1-D or winterized

2-D) diesel fuel, if available. At temperatures below

32°F (0°C), do not use summer-grade (2-D) diesel fuel.

CAUTION

Caterpillar

Do not rev the engine if the oil pressure gauge indi-

cates no oil pressure. Shut down the engine if no

Caterpillar electronic engines are designed to start at

oil pressure appears within approximately ten sec-

temperatures above 32°F (0°C) without using starting

onds. Check to determine the cause of the problem.

aids. If the temperature is below 32°F (0°C), startability

Operating the engine with no oil pressure will dam-

will be improved by the use of an automatic ether injec-

age the engine.

tion system and/or a water jacket heater.

Cold Weather Starting

CAUTION

Directing ether at the heater element in the intake

WARNING

air preheater could cause extensive engine damage.

Do not use any starting aid, such as ether, in en-

gines with an intake air preheater. This could cause

3.5

Engines

The intake air preheater is activated by turning the igni-

air preheater warms up. After the indicator goes out,

tion switch to the ON position. See Fig. 3.1. If the en-

start the engine.

gine is at normal temperature, the INTAKE HEATER

Run the engine slightly above idle until oil pressure

indicator goes out after two seconds.

shows on the gauge. If oil pressure doesn’t show on the

If the temperature is low enough to require use of the

gauge within 30 seconds of starting, turn the ignition

heater, the INTAKE HEATER indicator stays on while

switch to the OFF position and wait one minute; then

the intake air preheater warms up. After the indicator

repeat the starting procedure.

goes out, start the engine.

Mercedes-Benz

IMPORTANT: Attempting to start the engine before

the INTAKE HEATER indicator has gone out could

NOTE: An intake air preheater is optional on

result in excessive white smoke at startup.

Mercedes-Benz engines.

If the engine doesn’t start after 15 to 20 seconds of

The intake air preheater (if so equipped) is activated by

cranking, turn the ignition switch to the OFF position

turning the ignition switch to the ON position. See

and wait two minutes; then repeat the starting proce-

Fig. 3.1. If the engine is at normal temperature, the IN-

dure.

TAKE HEATER indicator goes out after two seconds.

If the temperature is low enough to require the heater,

Cummins

the INTAKE HEATER indicator stays on while the intake

The cold start system approved for use on Cummins

air preheater warms up. After the indicator goes out,

engines has been based upon starting aid capabilities

start the engine. If the engine doesn’t start after about

to -25°F (-32°C). For more information, see the Cum-

30 seconds of cranking, turn the ignition switch to the

mins Operation and Maintenance Manual.

OFF position and wait two minutes; then repeat the

starting procedure.

Turn the ignition switch to the ON position. See

Fig. 3.1. If the engine is at normal temperature, the IN-

NOTE: If the engine doesn’t start on the second

TAKE HEATER indicator goes out after two seconds.

try, wait at least five minutes before using the in-

If the temperature is low enough to require the heater,

take air preheater again.

the INTAKE HEATER indicator stays on while the intake

3.6

Engines

7. Make sure that the battery cable connections are

Starting After Extended

clean and tight. Check that the batteries are

Shutdown or Oil Change

charged.

An engine in storage for an extended period of time

8. Start the engine. See "Engine Starting" above.

(over winter, for example) may accumulate water in the

oil pan. Oil diluted by water cannot provide adequate

Engine Break-In

bearing protection at start-up. For this reason, change

the engine oil and filters after extended storage.

Caterpillar

Follow the steps below after an oil change or after the

Every Caterpillar engine must pass a full-load operation

engine has been shut down for more than three days:

test on a dynamometer before shipment, eliminating the

need for a break-in period. Only an initial operational

1. Make sure that the transmission is filled with the

correct type of fluid, as recommended by the trans-

check is necessary.

mission manufacturer.

Cummins

2. Make sure that the fuel tank is full. If air has en-

tered the fuel system, prime the fuel system, using

Cummins electronic engines are run on a dynamometer

the engine manufacturer’s instructions.

before being shipped from the factory. They do not re-

quire a break-in period.

3. If the engine is equipped with a fuel/water separa-

tor, drain off any accumulated water.

IMPORTANT: Special break-in oils are not recom-

4. Check the drive belts to make sure that they are in

mended for new or rebuilt Cummins engines.

good condition and properly adjusted. Replace any

drive belts that are cracked, worn, or glazed.

Mercedes-Benz

5. Check the turbocharger (if so equipped) for signs of

Every Mercedes-Benz engine is tested on a dynamom-

oil or exhaust leaks. Correct any problems before

eter before shipment. Therefore, no break-in period is

starting the engine.

necessary for the MBE900 engine. Before running the

engine for the first time, follow the instructions in the

6. Check the engine mounting bolts for tightness.

engine Operator’s Manual.

Tighten them if necessary.

3.7

Engines

Adequate maintenance of the engine, which is the re-

Engine Operation

sponsibility of the owner/operator, is essential to keep

Operating vehicles with diesel engines in areas where

the emission levels low.

there are concentrated flammable vapors (such as die-

The driver should be familiar with the vehicle warning

sel, gasoline, or propane fumes) can create a hazard-

system in order to bring the vehicle to a safe stop if the

ous situation. These vapors can be drawn into the en-

engine malfunctions. If the driver doesn’t understand

gine through the air intake, and cause engine

how the warning system works, an engine shutdown

overspeed. Be especially cautious of low-lying or

could occur, causing a safety hazard. See Chapter 2

closed-in areas, and always check for signs that flam-

for information on the control panel for these engines.

mable vapors may be present.

Caterpillar

DANGER

Proper operation and maintenance are key factors in

obtaining maximum life and economy from a vehicle

Don’t operate the engine in an area where flam-

engine. Follow the directions in the Caterpillar Opera-

mable vapors such as gasoline or diesel fumes are

tion and Maintenance Manualand this manual for

present. Shut down the engine when in an area

trouble-free, economical engine operation.

where flammable liquids or gases are being

handled. Failure to observe these precautions could

1. Operate the engine at low load. After normal oil

result in serious injury or death.

pressure is reached and the temperature gauge

begins to move, the engine may be operated at full

All diesel engines have been built to comply with the

load.

requirements of the Federal (U.S.) Clean Air Act. Once

an engine is placed in service, the responsibility for

2. Caterpillar electronic engines automatically idle at

meeting both state and local regulations is with the

1000 rpm for the correct warm-up time after a cold

owner/operator. Good operating practices, regular main-

engine start (less than 40°F [5°C]). These electronic

tenance, and correct adjustments are factors which will

engine systems will reduce the idle speed to 600

help to stay within the regulations.

rpm when the engine is warm enough to drive the

vehicle.

3.8

Engines

IMPORTANT: Fuel heaters used on vehicles with

rpm is needed to make upshifts under various con-

Caterpillar electronic engines could cause exces-

ditions. This progressive shifting technique will

lower fuel costs because the engine will be operat-

sive fuel temperatures that affect engine perfor-

ing at the lowest rpm needed to pull the load.

mance and operation of the electronic engine con-

trols. If a fuel heater is used, make sure that it has

NOTE: Caterpillar electronic engines can be pro-

thermostatic controls. If the fuel heater has a

grammed to limit engine rpm while the vehicle is

timer, set the timer to activate only for a limited

operated in the lower and higher gears. This fea-

period of time before the engine starts. Make sure

ture assists the driver in following progressive

that the fuel heater is used only for starting the

shifting techniques.

engine.

6. On uphill grades, allow the engine to lug downward

3. Avoid excess idling. If extended idle time is re-

to peak torque rpm (1440 to 1550 rpm) before

quired, control the engine speed to 1000 rpm or

downshifting. Continue to downshift until you reach

higher.

a gear that will maintain the desired speed.

4. Select a gear that allows a smooth, easy start with-

6.1

Continue to operate at peak torque rpm as

out increasing engine speed above low idle or slip-

long as the vehicle will maintain its speed.

ping the clutch. Engage the clutch smoothly. Jerky

6.2

If the grade decreases, begin to upshift

starts waste fuel and put stress on the drivetrain.

when the engine speed goes above 2000

It is not necessary to accelerate Caterpillar elec-

rpm.

tronic engines to governed speed in the lower

6.3

For the best fuel economy and performance,

gears to get the vehicle moving (except in a high-

control the engine speed within the range of

power demand situation such as starting on a

1400 to 2000 rpm.

grade).

7. On a downhill grade, do not coast or put the trans-

5. Continue to upshift until cruising speed is reached.

mission in Neutral (N). A simple rule to follow is to

Use only the rpm needed to make an upshift into

select the same gear (or one gear lower) than

the next gear. When cruising speed is reached, se-

would be needed to go up the grade.

lect the highest gear available that will pull the load.

Experience with your vehicle will show you what

3.9

Engines

7.1

Avoid downshifting on small hills, even if the

Cummins diesel engines are designed to operate

engine must be lugged down below peak

successfully at full throttle under transient condi-

torque rpm.

tions down to rated rpm. This is consistent with rec-

ommended operating practices.

7.2

On longer downhill grades, allow the engine

to lug to peak torque rpm before downshift-

Depending on the vehicle gearing, the posted

ing. If the engine speed stabilizes at peak

speed limit can sometimes allow operation in either

torque rpm, stay in that gear.

of the two top gears; however, for improved operat-

ing efficiency (fuel economy and engine life), oper-

7.3

Anticipate long steep downgrades. Reduce

ate in the top gear at reduced rpm, rather than in

vehicle speed before reaching the summit.

the next lower gear at the maximum rpm.

Select a gear that allows the engine to run

near the high engine limit (2900 rpm).

Cruise at partial throttle whenever road conditions

and speed requirements permit. This driving tech-

7.4

To maintain a safe speed and increase fuel

nique permits operating within the most economical

economy, minimize the amount of braking

power range of the engine.

needed.

When approaching a hill, open the throttle smoothly

Cummins

to start the upgrade at full power, then shift down

as needed, to maintain the optimum vehicle and

Follow the directions in the Cummins Operation and

engine speed. The high torque of Cummins engines

Maintenance Manual and in this manual for trouble-free,

may permit topping some grades without shifting.

economical vehicle engine operation.

Cummins engines are designed to operate over a

wide speed range. More frequent shifting than nec-

CAUTION

essary does not allow proper utilization of this flex-

ibility. The driver who stays in top gear and uses

Do not operate the engine at excessive full throttle

the wider speed range will achieve the best fuel

below the rated rpm for more than 30 seconds. This

economy.

can shorten the life of the engine and cause severe

The Cummins diesel engine is effective as a brake

engine damage.

on downhill grades, but take care not to overspeed

the engine going downhill. The governor has no

3.10

Engines

control over engine speed when the engine is being

(2) Shift to a lower gear. If the temperature does

pushed by the loaded vehicle.

not return to normal, shut down the engine.

Mercedes-Benz

CAUTION

While you are driving, watch for any signs of engine

Do not allow the engine to exceed its governed

problems. If the engine overheats, uses excessive fuel

speed, or serious engine damage could result.

or lubricating oil, vibrates, misfires, makes unusual

noises, or shows an unusual loss of power, shut down

7. Never turn the ignition switch to the OFF position

the engine as soon as possible and determine the

while going downhill. With the engine still in gear,

cause of the problem. Frequently, engine damage may

fuel pressure will build up against the shutdown

be avoided by a quick response to early indications of

valve and may prevent it from opening when the

ignition switch is turned to the ON position.

problems.

1. Use the tachometer to determine when to shift. Fol-

8. Use a combination of brakes and gears to keep the

vehicle under control at all times, and to keep the

low the pattern on the shift lever when moving

through the gears.

engine speed below the rated rpm.

9. Check the coolant temperature and oil pressure

2. Depending on the vehicle gearing, the posted

speed limit can sometimes allow operation in either

gauges frequently.

of the two top gears; however, for improved operat-

ing efficiency (fuel economy and engine life), oper-

CAUTION

ate in the top gear at reduced rpm, rather than in

the next lower gear at the maximum rpm.

Continuous operation below 140°F (60°C), above

3. Cruise at partial throttle whenever road conditions

212°F (100°C), or with the oil pressure below 10 psi

and speed requirements permit. This driving tech-

(69 kPa), can damage the engine.

nique permits operating within the most economical

10. If the engine starts to overheat, reduce the power

power range of the engine.

output of the engine. Do one, or both, of the follow-

ing: (1) Release pressure on the accelerator pedal;

3.11

Engines

4. Use lower gears in steep downhill driving. Normally,

If the engine coolant temperature becomes too

the gear used to descend a hill is the same gear

low, raw fuel will wash the lubricating oil off of the

used to climb a hill of the same grade.

cylinder walls and dilute the crankcase oil, causing

5. Never allow the engine to exceed the rated speed.

all moving parts of the engine to suffer from poor

Use the exhaust brake and the optional constant-

lubrication.

throttle brake (if so equipped) to lower engine rpm

below the rated speed.

Cruise Control

6. Never allow the engine to idle for more than 30

Use the ON/OFF switch on the instrument panel to acti-

minutes. Excessive idling can cause oil to leak from

vate the cruise control.

the turbocharger.

WARNING

CAUTION

Do not activate the fifth wheel air slider control

Stop the engine at the first sign of malfunction. Al-

valve when the vehicle is in motion. Doing so could

most all malfunctions give some warning to the op-

result in damage to the fifth wheel member, kingpin,

erator before significant damage occurs. Many en-

cab, or trailer, and ultimately, to the drivetrain. A

gines are saved because alert operators heed the

guard is positioned around the switch to prevent it

warning signs (sudden drop in oil pressure, un-

from being accidentally activated.

usual noises, etc.) and immediately shut down the

engine.

CAUTION

NOTE: Long periods of idling are not good for an

engine because the combustion chamber tempera-

Do not attempt to shift gears without using the

tures drop so low that the fuel may not burn com-

clutch when the cruise control is engaged. Failure

pletely. This will cause carbon to clog the injector

to follow this precaution will result in a temporarily

spray holes and piston rings, and may result in

uncontrolled increase in engine speed; transmis-

sion damage and gear stripping could result.

stuck valves.

1. To cruise at a particular speed:

3.12

Engines

1.1

Move the ON/OFF switch on the instrument

with Cummins engines if the ON/OFF switch is

panel to the ON position.

turned to OFF.

1.2

Accelerate to the desired speed.

Cold Weather Operation

1.3

Momentarily move the SET/RESUME switch

on the instrument panel to the SET position.

General Information

To disengage cruise control:

Satisfactory performance of a diesel engine operating in

2.1

Depress the brake pedal, or clutch pedal, or

low ambient temperatures requires modification of the

engine, surrounding equipment, operating practices,

2.2

Move the ON/OFF switch on the instrument

panel to the OFF position.

and maintenance procedures. The lower the tempera-

tures the greater the amount of modification required,

To resume a preselected cruise speed:

and yet with the modifications applied, the engines must

3.1

If the ON/OFF switch on the instrument

still be capable of operation in warmer climates without

panel is in the OFF position, move it to the

extensive changes.

ON position.

The following information is provided to engine owners,

3.2

Momentarily move the SET/RESUME switch

operators, and maintenance personnel on how cold

on the instrument panel to RESUME. Cruise

weather modifications can be applied to get satisfactory

will return to the last speed selected.

performance from their diesel engines.

There are three basic objectives:

To adjust cruise speed up or down, hold the

SET/RESUME switch on the instrument

• Reasonable starting characteristics followed by

panel at RESUME to accelerate or at SET to

practical and dependable warm up of the engine

decelerate.

and equipment.

NOTE: The resume vehicle speed memory is

• A unit or installation which is as independent as

not maintained if the ignition switch is turned

possible from external influences.

to the OFF position. Also, it is not maintained

3.13

Engines

• Modifications which maintain satisfactory operat-

taken, ordinary cold weather will not cause difficulty in

ing temperatures with a minimum increase in

starting, or loss of efficiency.

maintenance of the equipment and accessories.

For cold weather operation, use the following guide-

If satisfactory engine temperature is not maintained,

lines:

higher maintenance cost will result due to increased

1. When starting the engine in temperatures below

engine wear.

32°F (0°C), use engine lubricants of lower viscosity.

Special provisions to overcome low temperatures are

For specifications, see the Caterpillar Operation

definitely necessary, whereas a change to a warmer

and Maintenance Manual for your engine.

climate normally requires only a minimum of revision.

2. Use winter-grade (1-D or winterized 2-D) diesel

Most of the accessories should be designed in such a

fuel, if available. At temperatures below 32°F (0°C),

way that they can be disconnected so that there is little

do not use summer-grade (2-D) diesel fuel.

effect on the engine when they are not in use.

3. When the temperature is below freezing, use suffi-

IMPORTANT: If a winterfront is used on a vehicle

cient antifreeze solution in the cooling system to

with an electronic engine equipped with a charge

prevent freezing. See Group 20 of the School Bus

air cooler, make sure that there are slit openings

Chassis Maintenance Manual for specifications.

distributed across the face of the winterfront to

4. During cold weather, give more attention to the con-

allow airflow through the entire charge-air-cooler

dition of the batteries. See Group 15 and Group

core. Do not use a winterfront with closed areas

54 of the School Bus Chassis Workshop Manual for

that block uniform air flow across all sections of

detailed information.

the charge-air-cooler crossflow tubes. This will ad-

5. Idle the engine at 1000 to 1200 rpm. This will warm

versely affect the operation and durability of the

up the engine more quickly.

charge air cooler.

6. Customer parameters may include cold mode op-

eration. When the sum of the coolant temperature

Caterpillar

and the intake air temperature is below 127°F

If the engine is in good mechanical condition, and the

(35°C), the system puts the engine in cold mode,

precautions necessary for cold weather operation are

limiting engine power, advancing timing, and adjust-

ing the low idle to 1000 rpm to improve warm-up

3.14

Engines

time. The system will keep the engine in cold mode

• Electrical equipment capable of operating in the

until the temperature condition has been met. The

lowest expected temperature. All switches, con-

system will then stop the cold mode and allow the

nections, and batteries in the electrical system

engine to operate normally.

should be inspected, and kept in good condition

to prevent losses through poor contacts.

Cummins

Arctic specifications refer to the material and specifica-

tions of components needed for satisfactory engine op-

The two most commonly used terms associated with

eration in extremely low temperatures, down to -65°F

preparation of equipment for low temperature operation

(-54°C). Contact the nearest Freightliner dealer or

are "winterization" and "arctic specifications."

Cummins engine dealer, to obtain the special items re-

Winterization of the engine and/or components makes

quired.

starting and operating possible down to -25°F(-32°C).

This requires:

CAUTION

• Adequate lubrication with low-temperature lubri-

cating oils.

"Antileak" antifreezes are not recommended for use

• Protection from the cold air (insulation). The

in Cummins engines. Although these antifreezes are

metal temperature does not change, but the rate

chemically compatible with DCA water treatment,

of heat dissipation is affected.

the "antileak" agents may clog the coolant filters.

• Fuel of the proper grade for the lowest tempera-

For more information, see the Cummins Operation and

ture.

Maintenance Manual.

• Coolant containing 50% corrosion-resistant anti-

Mercedes-Benz

freeze.

• Using an engine block heater, oil pan heater, or

Take special precautions during cold weather. For ser-

coolant heater to raise the engine block and com-

vice products to use in cold weather, see the engine

ponent temperatures above -25°F (-32°C) for

Operator’s Manual.

starting in lower temperatures.

IMPORTANT: At outside temperatures below -4°F

(-20°C), a coolant preheater is recommended.

3.15

Engines

1. Check for cracks in the battery cases, corrosion of

the kerosene only when refilling the tank, and be-

the terminals, and the tightness of the cable clamps

fore adding the diesel fuel.

at the terminals. Charge the batteries to full capac-

NOTE: Engine power may drop according to the

ity. Replace any battery that is unable to hold full

charge or is physically damaged.

proportion of kerosene. For this reason, never add

more than 50 percent kerosene to the fuel.

2. Check the condition and tension of the poly-V belt.

3. Periodically check the coolant mixing ratio (concen-

Engine Shutdown

tration of antifreeze in the coolant). Add more if

necessary. The coolant mixing ratio should never

Caterpillar

rise above 60-percent antifreeze.

4. Use low-viscosity lubricating oils for adequate lubri-

CAUTION

cation.

5. At temperatures below 32°F (0°C), do not use

Stopping the engine immediately after it has been

summer-grade (2-D) diesel fuel. To avoid fuel prob-

working under load can result in overheating and

lems due to paraffin separation, use winter-grade

accelerated wear of the engine components. Exces-

(1-D or winterized 2-D) diesel fuel only.

sive temperatures in the turbocharger centerhous-

ing will cause oil coking problems. Follow the pro-

cedure, outlined below, to allow the engine to cool.

WARNING

1. With the vehicle stopped, set the parking brake.

The addition of kerosene lowers the flash point of

Reduce engine speed to a low idle.

diesel fuel. To prevent fire and risk of injuries due

2. Place the transmission shift lever in Neutral (N).

to burning, do not smoke or use open flames

around fuel mixed with kerosene. Comply with all

NOTE: If the engine has been operating at low

appropriate safety regulations.

loads, run it at low idle for 30 seconds before

shutting it down. If the engine has been operating

6. When winter-grade diesel fuel is not adequate, it is

possible to mix kerosene with the diesel fuel. Add

at highway speed or at high loads, run it at low

3.16

Engines

idle for 3 minutes to reduce and stabilize internal

Cummins

engine temperatures before shutdown.

1. With the vehicle stopped, apply the parking brake,

3. Turn the ignition switch to the OFF position and

and place the transmission in Neutral (N).

shut down the engine.

2. Idle the engine for three to five minutes before

4. After shutting down the engine, fill the fuel tank.

shutting it down. This allows the lubricating oil and

the water to carry heat away from the combustion

5. Check the crankcase oil level with the engine shut

down. Maintain the oil level between the ADD and

chambers, bearings, shafts, etc. This is especially

important with turbocharged engines. The extreme

FULL marks on the dipstick.

heat may cause bearings to seize or oil seals to

6. If temperatures below 32°F (0°C) are expected, al-

leak.

low the engine water jacket expansion tank to cool;

then, check the coolant for proper antifreeze protec-

IMPORTANT: Bearings and seals in the turbo-

tion. Add antifreeze, if required. For additional infor-

charger are subjected to the high heat of combus-

mation, see Group 20 of the School Bus Chassis

tion exhaust gases. While the engine is running,

Maintenance Manual.

this heat is carried away by oil circulation, but if

the engine is shut down suddenly, the turbo-

IMPORTANT: The cooling system must be able to

charger temperature may rise as much as 115°F

protect against freezing to the lowest expected

(46°C).

outside temperature.

7. Repair any leaks, perform minor adjustments,

NOTE: Long periods of idling are not good for an

tighten loose bolts, etc. Observe the vehicle mile-

engine because the combustion chamber tempera-

age or the service meter reading, if so equipped.

tures drop so low that the fuel may not burn com-

Perform periodic maintenance as instructed in the

pletely. This will cause carbon to clog the injector

Maintenance Interval Schedule in the Caterpillar

spray holes and piston rings, and may result in

Operation and Maintenance Manual.

stuck valves.

3. Do not idle the engine for more than 10 minutes.

3.17

Engines

1. With the vehicle stopped, apply the parking brake

CAUTION

and place the transmission in Neutral (N).

Stop the engine at the first sign of malfunction. Al-

CAUTION

most all malfunctions give some warning to the op-

erator before significant damage occurs. Many en-

Idle the engine one to two minutes before shutting

gines are saved because alert operators heed the

it down, if this can be done without damage to the

warning signs (sudden drop in oil pressure, un-

engine. After hard operation, shutting down the en-

usual noises, etc.) and immediately shut down the

gine without idling may cause damage to the turbo-

engine.

charger.

4. Turn the ignition switch to the OFF position and

2. Allow the engine to idle one to two minutes before

shut down the engine.

shutting it down. This allows the lubricating oil and

the coolant to carry heat away from the combustion

Mercedes-Benz

chambers, bearings, shafts, and seals. The extreme

If any of the following occur, shut down the engine im-

heat may cause bearings to seize or oil seals to

mediately.

leak.

• The oil pressure gauge needle swings back and

IMPORTANT: Bearings and seals in the turbo-

forth or falls sharply.

charger are subjected to the high heat of combus-

tion exhaust gases. While the engine is running,

• Engine power and rpm fall even though the ac-

celerator pedal remains steady.

this heat is carried away by oil circulation, but if

the engine is shut down suddenly, the turbo-

• The exhaust pipe gives off heavy smoke.

charger temperature may rise as much as 115°F

• The coolant and/or oil temperature gauge read-

(46°C).

ings climb abnormally.

• Abnormal sounds suddenly occur in the engine or

turbocharger.

3.18

Engines

speed is between 900 and 2,700 rpm. Depressing the

CAUTION

accelerator or clutch pedal deactivates the exhaust

brake. The ABS system, when active, also deactivates

Except in emergency, do not shut down the MBE900

the exhaust brake.

engine when the coolant temperature is above

When both the exhaust brake and the constant throttles

194°F (90°C). To do so could damage the engine.

are installed, a three-position switch on the dash con-

3. Turn the ignition switch to the OFF position and

trols the engine braking system. The exhaust brake can

shut down the engine.

be used alone or together with constant-throttle valves

for steep or long grades. Like the engine brake, the

constant throttles are deactivated when the accelerator

Engine Braking System

or clutch pedal is depressed. The ABS system, when

(optional)

active, also deactivates constant-throttle braking.

Constant-Throttle Valves (MBE900

Exhaust Braking System

only)

(optional)

To increase braking performance, the Mercedes-Benz

MBE900 engine can be equipped with constant throttles

General Information

in each combustion chamber. Small valves built into the

An exhaust brake is an optional auxiliary braking sys-

cylinder head allow a small amount of compressed air

tem that assists but does not replace the service brake

to escape through the exhaust port during the combus-

system. The exhaust brake switch, located on the con-

tion stroke. The constant-throttle valves are open during

trol panel, (in combination with the accelerator and

the entire time that the engine brake is activated. Al-

clutch pedals) allows the driver to make maximum use

though some braking ability is lost because the valves

of the exhaust brake in off-highway and mountain driv-

are constantly open, constant-throttle braking is quieter

ing as well as in traffic or in high-speed highway driving.

in operation than other types of engine brakes.

The exhaust brake is a butterfly valve mounted in the

When only the exhaust brake is installed, a two-position

exhaust pipe. When the driver’s foot is not on the accel-

switch on the dash controls the engine braking system.

erator pedal and the exhaust brake switch is in the ON

The exhaust brake is only active when the engine

3.19

Engines

position, an air cylinder shuts the butterfly valve which

Apply the service brakes to reduce the engine rpm or

restricts the flow of exhaust gases and retards the en-

make a slower descent by using a lower gear.

gine. This retarding action is carried through the engine

and drivetrain, slowing the vehicle and reducing the

WARNING

need for frequent service brake applications.

IMPORTANT: Exhaust brakes are not intended for

Do not use the exhaust brake when driving on slip-

use as the primary braking system during vehicle

pery or low traction road surfaces. Failure to follow

this precaution could result in a loss of vehicle con-

operation.

trol and possible personal injury or property dam-

Starting the Engine

age.

Before starting the engine, make sure that the exhaust

Exhaust Brake Operating Characteristics

brake switch is in the OFF position. Do not turn the ex-

When you remove your feet from both the accelerator

haust brake on until the engine has reached normal op-

and the clutch pedal and the exhaust brake switch is in

erating temperatures.

the ON position, the exhaust brake is applied. The fol-

lowing conditions should exist if the brake is operating

Driving Downhill

properly:

While approaching a steep grade, make sure that the

• A slight change in the sound of the engine may

exhaust brake switch is in the ON position. The exhaust

be noticed when the exhaust brake is applied.

brake comes on as soon as you remove your foot from

the accelerator pedal. While going down the grade, use

• Exhaust smoke should appear normal.

a low enough gear to safely descend with a minimum

• Engine temperature should remain in the normal

application of the service brakes. As a general guide-

operating range.

line, use the same gear as you would to ascend the hill.

• Road speed usually decreases when the exhaust

brake is applied during a descent. When the ve-

CAUTION

hicle is carrying a heavy load or the grade is ex-

tremely steep, you may need to apply the service

Do not allow the engine to exceed its governed

brakes occasionally.

speed, or serious engine damage could result.

3.20

Engines

• Do not expect a retarding effect similar to sudden

Pacbrake Operation

hard application of the service brakes. The ex-

The Pacbrake is controlled by the exhaust brake switch

haust brake retards the vehicle with a smooth

and the throttle pedal. All applications are additionally

braking effect.

affected, controlled, or governed by engine speed

• During a descent, the tachometer usually shows

through transmission gear selection. The Allison

a drop in rpm depending on the grade and the

MD3060 transmission has automatic downshifting when

vehicle load.

the exhaust brake is requested. See the information on

the "Allison World Transmission" later in this chapter.

• Depending on the grade and vehicle load, you

may or may not feel the retarding force acting

On some applications, when the Pacbrake is in use, it

against your body when the brake is applied. The

may be necessary to check that the cruise control is not

retarding force of the brake may not always be

set and that the throttle is in the idle position.

noticed, but it is actually preventing the vehicle

On some applications the engine, transmission, cruise

from going much faster.

control, and the Pacbrake exhaust brake may electroni-

cally interact with each other, which automatically acti-

Shutting Down the Engine

vates their functions. Following are some examples of

Make sure that the exhaust brake is turned off before

the programmed options that may be available with the

shutting down the engine.

cruise control in the ON position:

• The coast mode engages the Pacbrake when the

Pacbrake^® Exhaust Brake

service brake is applied and disengages when

The Pacbrake exhaust brake is intended as a supple-

the service brake is released.

ment to the service brakes and will not bring the vehicle

• The latch mode engages the Pacbrake when the

to a complete stop. The Pacbrake will assist in the con-

service brake is applied and the Pacbrake re-

trol or reduction of road speed in conjunction with, or

mains on after the service brake is released. The

independent of, the service brakes. The amount of re-

Pacbrake is disengaged when another input (de-

tarding or braking force is controlled by the driver.

pressing the throttle or clutch, engine speed

drops below 800 rpm, or the exhaust brake

switch is turned off) is supplied.

3.21

Engines

• The manual mode does not require the cruise

Allison World Transmission

control switch to be on and operates the

Pacbrake exhaust brakes on engines that are used with

Pacbrake manually at the driver’s discretion.

the Allison World Transmission MD series, and 2000

The amount of braking power the engine will develop is

and 2400 series, are interfaced with the transmission

related to the speed (rpm) of the engine. The higher the

electronic control module (ECM). An exhaust brake en-

engine rpm, the greater the retarding power.

abled transmission ECM will usually provide converter

lockup in gears Two (2) through Six (6). Effective ex-

Certain conditions may require that the transmission be

haust braking begins when the transmission automati-

downshifted in order to generate adequate rpm for the

cally downshifts into Fifth (5) gear (62 mph [100 km/h]

amount of retarding power required. Pacbrake exhaust

or less). Once on, the Pacbrake exhaust brake will con-

brakes are designed and approved for safe use at 300

trol road speed and/or slow the vehicle sufficiently so

rpm above the engine’s maximum governed rpm. See

that the transmission will automatically downshift, if nec-

the engine manufacturer’s specifications.

essary, to Allison’s preselect mode.

NOTE: Starting the engine, idling for short periods

The preselect mode is normally assigned to Second (2)

of time, and then shutting down the engine is not

gear; however, the transmission can be reprogrammed

recommended. During a cold engine start-up,

by an Allison Transmission Distributor to Third (3) or

enough moisture is developed within the engine

Fourth (4) gear should the operator desire. If additional

and the exhaust system to create a corrosion haz-

retarding power is required before the automatic down-

ard that could affect the future operation of the

shifting occurs, you can select a lower transmission

Pacbrake. The brake housing may trap water in

gear on the Allison shift selector.

the valve shaft bore causing corrosion in an im-

proper or non-functioning brake. If it is necessary

to periodically start the engine, it is recommended

that normal operating temperatures be attained

before shutting down the engine.

3.22

Clutches

General Information

Clutch Operation

The major reason that clutches wear out too soon is

Starting the Vehicle in the Correct

because they have been overheated. Clutches are de-

Gear

signed to absorb and dissipate more heat than encoun-

tered in typical operation. The temperatures developed

NOTE: Manual transmission vehicles are equipped

in typical operation will not break down the clutch fric-

with an ignition interlock switch. The engine will

tion surfaces. However, if a clutch is slipped exces-

not start until the clutch has been fully depressed.

sively, or required to do the job of a fluid coupling, high

temperatures develop quickly and destroy the clutch.

To drive forward, always start in First (1) gear. After the

Temperatures generated between the flywheel, driven

clutch is fully engaged, accelerate to the correct rpm for

discs, and pressure plates can be high enough to cause

the upshift into the next higher gear.

the metal to flow and the friction facing material to char

and burn.

Gear Shifting Techniques

Slipping and excessive heat are practically nonexistent

Many drivers upshift into the next gear, or even skip-

when a clutch is fully engaged. But during the moment

shift into a higher gear, before the vehicle has reached

of engagement, when the clutch is picking up the load,

the correct speed. This type of shifting is almost as bad

it generates considerable heat. An incorrectly adjusted

as starting off in a gear that is too high, since the en-

or slipping clutch will rapidly generate sufficient heat to

gine rpm and vehicle speeds are too far apart, requiring

destroy itself.

the clutch to absorb the speed difference by generating

heat. For transmission operating instructions, see

The most important items that a driver should be aware

Chapter 5.

of to ensure long service life of the clutch include: start-

ing in the correct gear, recognizing clutch malfunctions,

and knowing when to adjust a clutch.

Vehicle Overload, or Overloading the

Clutch

Clutches are designed for specific vehicle applications

and loads. These limitations should not be exceeded.

4.1

Clutches

CAUTION

WARNING

Overloading will not only result in damage to the

Do not coast with the clutch released (pedal de-

clutch, but also to the entire power train.

pressed) and the transmission in gear. High driven

disc rpm could cause the clutch facing to be thrown

Riding the Clutch Pedal

off the disc. Flying debris could cause injury to per-

sons in the cab.

Riding the clutch pedal is destructive to the clutch,

since partial clutch engagement permits slippage, gen-

Engaging the Clutch While Coasting

erating excessive heat. Riding the clutch pedal will also

put a constant thrust load on the release bearing, which

Engaging the clutch while coasting can result in tremen-

can thin out the lubricant. Release bearing failures can

dous shock loads and possible damage to the clutch,

be attributed to this type of misuse.

as well as to the entire drivetrain.

Holding the Vehicle on an Incline With

Reporting Erratic Clutch Operation

a Slipping Clutch

Promptly

A slipping clutch accumulates heat faster than it can be

Report erratic clutch operation as soon as possible so

dissipated, resulting in early clutch failures. Never use

that maintenance personnel have a chance to inspect

the clutch to hold your position on a hill.

the clutch components.

Coasting With the Clutch Released

Clutch Adjustments

(pedal depressed) and the

Some clutches have an internal adjustment. See the

Transmission in Gear

applicable section in Group 25 of the School Bus Chas-

sis Workshop Manual for clutch adjustment procedures

Coasting with the clutch released and the transmission

and specifications.

in gear can cause high driven disc rpm through multipli-

cation of ratios from the final drive and transmission.

4.2

Transmissions

Fuller Straight-Shift

Transmissions

General Information

Fuller FS-4205A/B, FS-5205A/B, and FS-6305A/B

transmissions have five forward speeds and one Re-

verse (R) speed. See Fig. 5.1 for the shift pattern.

10/19/2000

f260085

Fig. 5.2, Shift Pattern, FS-5306A and FS-6306A

Operation

NOTE: Always use First (1) gear when starting to

move the vehicle forward.

1. Depress the clutch pedal and engage First (1) gear.

03/12/96

f260080

2. Accelerate and gradually engage (release) the

clutch pedal to get moving.

Fig. 5.1, Shift Pattern, FS-4205A/B, FS-5205A/B, and

FS-6305A/B

3. Accelerate smoothly until ready to upshift to the

next gear.

Fuller FS-5306A and FS-6306A transmissions have six

4. Release the accelerator, disengage the clutch, up-

forward speeds and one Reverse (R) speed. See

shift, engage the clutch, and accelerate.

Fig. 5.2 for the shift pattern.

5. Continue upshifting using the sequence described

These transmissions are designed for use with fuel

in the previous steps. Follow the pattern on the shift

economy engines where a minimum of shifting is de-

lever.

sired and less gear reduction is acceptable.

5.1

Transmissions

6. When downshifting, shift progressively down

gears that are selected automatically according to the

through each successive lower gear as follows:

speed of the vehicle, engine temperature, and throttle

position.

When the engine speed drops to the same rpm to

which it fell immediately after upshifting to that

NOTE: Vehicles equipped with an Arens shift-by-

same gear, disengage the clutch and move the shift

wire shift control system have an electronic push-

lever to the next lower gear; engage the clutch

button selector similar to that described below for

smoothly.

MD-series transmissions.

Continue downshifting, as conditions require, using

MD-series automatic transmissions have six forward

the same sequence described above.

speeds and one Reverse (R) speed. See Fig. 5.4.

These transmissions have electronic shift controls that

IMPORTANT: Do not rest your foot on the clutch

can be programmed to allow the use of different num-

pedal while driving. This causes partial clutch dis-

bers of geared speeds. For instance, the transmission

engagement, and will cause premature clutch

can be programmed to operate as a four-speed, five-

wear.

speed, or six-speed unit in the "primary" shift mode. If

needed, a "secondary" shift mode can be programmed

NOTE: Always disengage the clutch completely

to provide another shift configuration to optimize vehicle

when shifting gears. Double-clutching is unneces-

use under different operating conditions. To activate a

sary.

secondary shift mode, or other special function pro-

grammed into the electronic control unit (ECU), depress

Allison Automatic

the mode button. "Mode On" is displayed in the indica-

tor panel just above the push-buttons. A label just

Transmissions

above the Mode button identifies the special function.

General Information

NOTE: Each time that a push-button is depressed

on the shift selector, a short beep is heard. This

Allison four-, five-, and six-speed automatic transmis-

indicates that the ECU has received input to

sions have six shift positions on the selector lever. See

change operation.

Fig. 5.3. The selector lever is lighted for night driving.

Each forward shift position provides a range of forward

5.2

Transmissions

The MD-series transmission system is designed to warn

the driver of transmission malfunctions. The driver of a

vehicle equipped with one of these transmissions

should know the extent of the warning system in order

to safely operate the vehicle. See Chapter 2 for infor-

mation on the warning system.

10/31/94

f600369a

1. Digital Display

2. Mode Identification

Fig. 5.4, Allison Push-Button Shift Selector

Operation

07/09/96

f270004

IMPORTANT: Do not race the engine when shifting

Fig. 5.3, Shift Indicator Lever

from Neutral (N) into a Drive (D) gear range.

5.3

Transmissions

1. Use Reverse (R) to back the vehicle. Completely

for climbing long grades and for engine braking

stop the vehicle before shifting from a forward gear

when descending moderately steep grades. To pre-

to Reverse (R) or from Reverse (R) to a forward

vent excessive engine speed, do not drive faster

gear. There is only one Reverse (R) gear.

than 45 miles per hour (72 km/h) in Second (2) or

Third (3).

2. Use Neutral (N) and set the parking brake to park

the vehicle with the engine running or shut down.

5. Use First (1) for climbing very steep grades and for

The engine may be started in this position. Always

engine braking at low speeds when going downhill.

chock the tires for hilly or off-road parking.

To prevent excessive engine speed, do not drive

faster than 25 miles per hour (40 km/h) in First (1).

CAUTION

NOTE: In the lower gear ranges, the transmission

will not upshift above the highest gear selected

Do not allow the vehicle to coast in neutral. This

unless the engine governed speed is exceeded.

can result in severe transmission damage. Also, no

engine braking is available.

MD-Series Transmissions

3. Select Drive (D) for all normal driving conditions.

The vehicle will start out in First (1) gear, and as

CAUTION

speed increases, the transmission will upshift

through each gear automatically. As the vehicle

The engine should never be operated for more than

slows down, the transmission will downshift to the

30 seconds at full throttle with the transmission in

correct gear automatically.

gear and the output stalled. Prolonged operation of

this type will overheat the transmission fluid and

Occasionally the road, load, or traffic conditions

will result in severe damage to the transmission.

make it desirable to restrict the automatic shifting to

a lower range. The lower the gear range, the

1. Start the engine, then check the digital display on

greater the engine braking power.

the push-button shift selector. Under Select at the

top of the unit, the display shows the primary shift

4. Use Second (2) or Third (3) for slow driving in

mode. Under Monitor, the gear that is engaged is

heavy city traffic, or on mountain roads when more

displayed.

precise speed control is desirable. Use them also

5.4

Transmissions

Use the UP or DOWN arrow buttons on the shift

WARNING

selector to reach the desired gear. The Select indi-

cator will display your choice, and the Monitor indi-

Never shift from neutral (N) to drive (D) or reverse

cator will show the selected gear once it is reached.

(R) at engine speeds above idle. The vehicle will

NOTE: In the lower gear ranges, the transmission

lurch forward or backward, which could cause prop-

erty damage and personal injury.

will not upshift above the highest gear selected

unless the engine governed speed is exceeded.

2. Use Reverse (R) to back the vehicle. Completely

stop the vehicle before shifting from a forward gear

5. Engage Neutral (N) and apply the parking brake

to Reverse (R) or from Reverse (R) to a forward

when the vehicle is parked with the engine running.

gear. There is only one Reverse (R) gear.

3. Select Drive (D) for all normal driving conditions.

CAUTION

The vehicle will start out in First (1) gear, and as

speed increases, the transmission will upshift

Do not allow the vehicle to coast in neutral. This

through each gear automatically. As the vehicle

can result in severe transmission damage. Also, no

slows down, the transmission will downshift to the

engine braking is available.

correct gear automatically.

Safety Precautions

The pressure of your foot on the accelerator pedal

Do the following steps if you have to leave the cab with

influences the automatic shifting. When the pedal is

the engine running (for example, when checking the

fully depressed, the transmission will automatically

transmission fluid):

upshift near the governed speed of the engine. A

partially depressed position of the pedal will cause

1. Bring the vehicle to a complete stop using the ser-

the upshifts to occur at a lower engine speed.

vice brakes.

4. Occasionally the road, load, or traffic conditions

2. Put the transmission in Neutral (N).

make it desirable to restrict the automatic shifting to

3. Ensure that the engine is at low idle rpm (below

a lower range. The lower the gear range, the

1000).

greater the engine braking power.

5.5

Steering System

General Information

CAUTION

When there is no load on the vehicle, and the front tires

are pointed straight ahead, the steering wheel spokes

Never steam clean or high-pressure wash the steer-

should be at the 9 and 3 o’clock positions, or within 10

ing gear. Internal damage to gear seals and ulti-

degrees to either side. See Fig. 6.1. See Group 46 of

mately the steering gear can result.

the School Bus Chassis Workshop Manual for steering

adjustment procedures.

Power Steering System

The power steering system consists of a steering gear

(which includes a manual steering mechanism, a hy-

draulic control valve, and a hydraulic power cylinder),

hydraulic hoses, power steering pump, reservoir, and

other components. The power steering pump, driven by

the engine, provides the power assist for the steering

system. If the engine is not running, there is no power

10°

assist.

If the power-assist feature does not work due to hydrau-

lic fluid loss, steering pump damage, or some other

10°

cause, bring the vehicle to a safe stop. Do not drive the

vehicle until the cause of the problem has been cor-

rected.

11/15/2000

f460307b

9 o’Clock

3 o’Clock

WARNING

Fig. 6.1, Steering Wheel Centered

Driving the vehicle without the power-assist feature

of the steering system requires much greater effort,

especially in sharp turns or at low speeds, which

could result in an accident and possible injury.

6.1

Steering System

Drivers should use the power available with a power

steering system carefully. If the front tires become

lodged in a deep chuckhole or rut, drive the vehicle out

instead of using the steering system to lift the tires from

the hole. Also avoid turning the tires when they are

against a curb, as this places a heavy load on steering

components and could damage them.

Tilt/Telescope Steering Column

(optional)

Adjust the seat to a comfortable position. If the vehicle

is equipped with a tilt/telescope steering column, pull

the control lever on the column upward and adjust the

steering wheel to the desired position. See Fig. 6.2.

Push the lever downward and extend or retract the

steering column as desired. Release the control lever to

lock the steering column in place.

11/15/2000

f461176a

If the vehicle is equipped with a tilt-only column, adjust

1. Tilt/Telescope Lever

the steering wheel with either a control lever on the col-

umn or a foot-operated control valve located to the left

Fig. 6.2, Tilt/Telescope Steering Column

of the clutch or brake pedal. See Fig. 6.3. Release the

control lever or valve to lock the steering column in

WARNING

place.

Make sure that the control lever or valve is released

and that the steering column is locked before driv-

ing the vehicle. Never tilt or telescope the column

while driving the vehicle. Doing so could cause loss

6.2

Brake System

4. Adjust the parking brake linkage and hand lever

Driveline Parking Brake

knob to suit your load and road grade conditions.

Burnishing

Hydraulic Brake System

WARNING

General Information

Vehicles equipped with hydraulic brakes are

The Bendix hydraulic brake system includes a power

equipped with a driveline parking brake. If your ve-

booster, master cylinder, reservoir , hydraulic lines, a

hicle is equipped with a driveline parking brake, you

brake rotor on each wheel hub, and a brake caliper and

must burnish the parking brake before you put the

pad assembly at each rotor. See Fig. 7.1.

vehicle into regular service. An unburnished park-

ing brake may not have full effectiveness. If the

IMPORTANT: Make sure that the fluid level in the

parking brake slips, personal injury or property

master cylinder reservoir is up to the ridge that

damage could result.

surrounds the reservoir. Use only heavy-duty

brake fluid, DOT 3, in the hydraulic brake system.

Burnish the driveline parking brake as follows:

The master cylinder controls braking power to the front

1. Load the vehicle to its gross vehicle weight (GVW).

and rear brakes. The power booster is attached to the

2. With the parking brake released, turn the knob on

rear of the master cylinder and is connected to the

the end of the parking brake handle clockwise to

power steering system (which provides pressurized

adjust the parking brake. Adjust the brakes until you

power steering fluid). An electrically-powered "reserve"

can stop the vehicle traveling at 10 mph (16 km/h)

pump operates if there is inadequate fluid flow from the

within stopping distances of 21 to 36 feet (8 to 11

power steering pump to the power booster. The brake

m) using only the parking brake.

system warning light comes on if there is a problem

within the system. Bring the vehicle to a safe stop and

3. Using only the parking brake, make 10 stops from

correct the problem before continuing operation of the

10 mph (16 km/h) on a hard dry road surface. After

vehicle. See Group 42 of the School Bus Chassis

each stop, release the parking brake and drive the

Workshop Manual for hydraulic brake system trouble-

vehicle at 20 mph (32 km/h) for 2.5 miles (4 km) to

shooting and adjustment procedures.

cool the brake.

7.1

Brake System

does not go out, correct the problem before continuing

operation of the vehicle.

During normal brake stops, depress the foot brake con-

trol pedal until braking action slows the vehicle. In-

crease or decrease the pressure on the pedal so that

the vehicle comes to a smooth, safe stop. When the

forward speed of the vehicle has decreased to almost

the idling speed of the engine, push the clutch pedal in

(if so equipped), and shift the transmission into Neutral

(N). Apply the hand parking brake if the vehicle is to be

parked.

Meritor WABCO^® Antilock Braking

System (ABS), Hydraulic Brake

Systems

10/31/94

f460513a

The Meritor WABCO^® Antilock Braking System (ABS) is

an electronic wheel speed monitoring and control sys-

A. Open caps and check fluid level.

tem that works with the hydraulic brake system. ABS

B. Fill to this level.

passively monitors vehicle wheel speed at all times, but

Fig. 7.1, Hydraulic Brake Reservoir

controls wheel speed during an emergency or reduced-

traction stop. In normal braking applications, the stan-

dard hydraulic brake system is in effect.

Operation

Before driving the vehicle, secure all loose items in the

IMPORTANT: For proper ABS system operation,

cab so that they will not fly forward during a full brake

do not change tire sizes. The sizes of the tires in-

application. Check that the brake system warning light

stalled during production are programmed into the

is out after releasing the hand brake. If the warning light

electronic control unit. Installing different sized

7.2

Brake System

tires could result in inaccurate wheel speed sig-

and to protect the components from corrosion.

nals to the ECU resulting in reduced braking force,

Clean more frequently when unusually corrosive

chemicals are being used.

which could lead to longer stopping distances.

ABS includes signal-generating tone wheels and sen-

IMPORTANT: During winter months in areas where

sors located in the wheel hubs of each sensed axle.

corrosive materials are used on the highways, pe-

The sensors transmit vehicle wheel speed information

riodically clean the underside of the vehicle to en-

to an electronic control unit (located on the frontwall)

sure proper ABS functioning.

that interprets these signals to calculate wheel speed

The electronic control unit also has a safety circuit that

and a vehicle reference speed. If the calculations indi-

constantly monitors the wheel sensors, brake pressure

cate wheel lockup, the appropriate control circuit signals

modulator, and the electrical circuitry. The dash warning

the brake pressure modulator to increase or decrease

light (ABS) comes on after the ignition switch is turned

braking pressure until wheelslip has been corrected.

to the ON position. Once the vehicle moves faster than

about 4 mph (6 km/h), the warning light goes out only if

CAUTION

all of the vehicle’s ABS components are working.

If, during vehicle operation, the safety circuit senses a

An accumulation of road salt, dirt, or debris on the

failure in any part of the ABS system (a sensor, brake

ABS tone wheels and sensors can cause the ABS

pressure modulator, wiring connection, short circuit,

warning light to come on. If the ABS light does

etc.), the warning light (ABS) comes on and the control

come on, the tone rings and sensors should be in-

circuit where the failure occurred is switched to normal

spected for corrosion and serviced if necessary.

braking action. Even if the ABS system is partially or

The service should include cleaning of the tone

completely inoperative, normal braking ability is main-

rings and sensors. If any tone ring on a vehicle

tained. An exception would be if the brake pressure

shows severe corrosion, all tone rings on that ve-

modulator, or hydraulic fluid line is damaged. As these

hicle should be replaced.

components are an integral part of the hydraulic brake

During winter months in areas where corrosive ma-

system, normal braking may be impaired or inoperative.

terials are used on the highways, periodically clean

IMPORTANT: If any of the ABS warning lights do

the underside of the vehicle, including the tone

not work as described above, or come on while

rings and sensors, to ensure proper ABS function

7.3

Brake System

driving, repair the ABS system immediately to en-

WARNING

sure full antilock braking capability.

During emergency or reduced-traction stops, fully de-

Do not operate the vehicle with the front brakes

press the brake pedal until the vehicle comes to a safe

backed off or disconnected. Backing off or discon-

stop; do not pumpthe brake pedal. With the brake pedal

necting the front brakes will not improve vehicle

fully depressed, the ABS system will control all wheels

handling and may lead to loss of vehicle control

to provide steering control and a reduced braking dis-

resulting in property damage or personal injury.

tance.

Loss of air pressure in the primary system causes the

Although the ABS system improves vehicle control dur-

rear service brakes to become inoperative; front brakes

ing emergency braking situations, the driver still has the

will continue to be operated by secondary system air

responsibility to change driving styles depending on the

pressure.

existing traffic and road conditions. For example, the

ABS system cannot prevent an accident if the driver is

Loss of secondary system air pressure causes the front

axle brakes to become inoperative; rear service brakes

speeding or following too closely on slippery road sur-

faces.

will continue to be operated by the primary system.

Before driving your vehicle, allow time for the air com-

Air Brake System

pressor to build up a minimum of 95 psi (655 kPa) pres-

sure in both the primary and secondary systems. Moni-

General Information

tor the air pressure system by observing the dual

system air pressure gauges and the low-air-pressure

A dual air brake system consists of two independent air

warning light and buzzer. The warning light and buzzer

brake systems which use a single set of brake controls.

shut off when air pressure in both systems reaches 64

Each system has its own reservoir, plumbing, and brake

to 76 psi (441 to 524 kPa).

chambers. The primary system operates the service

brakes on the rear axle; the secondary system operates

The warning light and buzzer come on if air pressure

the service brakes on the front axle.

drops below 64 to 76 psi (441 to 524 kPa) in either sys-

tem. If this happens, check the air system pressure

7.4

Brake System

gauges to determine which system has low air pres-

Operation

sure. Although the vehicle’s speed can be reduced us-

ing the foot brake control pedal, either the front or rear

Before driving the vehicle, secure all loose items in the

service brakes will not be operating, causing a longer

cab so that they will not fly forward during a full brake

stopping distance. Bring the vehicle to a safe stop, and

application.

have the air system repaired before continuing.

During normal brake stops, depress the foot brake con-

trol pedal until braking action slows the vehicle. In-

WARNING

crease or decrease the pressure on the pedal so that

the vehicle comes to a smooth, safe stop. When the

Do not drive the vehicle with the parking brakes

forward speed of the vehicle has decreased almost to

caged. If the vehicle is driven with the parking

the idling speed of the engine, push the clutch pedal in

brakes caged, there would be no means of stopping

(if so equipped), and shift the transmission into Neutral

the vehicle if a complete loss of air pressure oc-

(N). Apply the parking brake if the vehicle is to be

curred. This could result in serious personal injury

parked.

or vehicle damage. Before caging the spring park-

The yellow diamond-shaped knob on the control panel

ing brakes, make the connection to a towing vehicle

actuates the parking brake valve. See Fig. 7.2. Pull the

or chock the tires.

knob out to apply the parking brake.

NOTE: Before a vehicle with insufficient system air

pressure can be moved, the spring parking brakes

must be released by applying an external air

source, or by manually caging (manually releas-

ing) the parking brake springs.

SYSTEM

PARK

After correcting the brake system problem, uncage the

spring parking brakes before resuming normal vehicle

operation.

02/09/95

f600631

Fig. 7.2, Parking Brake Valve Knob

7.5

Brake System

Meritor WABCO^® Antilock Braking

WARNING

System (ABS), Air Brake Systems

If the vehicle is equipped with an air suspension

The Meritor WABCO^® Antilock Braking System (ABS) is

system, do not move the vehicle with the air sus-

an electronic wheel speed monitoring and control sys-

pension deflated. Doing so could result in a loss of

tem that works with the air brake system. ABS passively

vehicle control, possibly causing personal injury

monitors vehicle wheel speed at all times, but controls

and property damage.

wheel speed during an emergency or reduced-traction

stop. In normal braking applications, the standard air

CAUTION

brake system is in effect.

IMPORTANT: For proper ABS system operation,

Do not use the spring parking brakes if the service

do not change tire sizes. The sizes of the tires in-

brakes are hot, such as after descending a steep

stalled during production are programmed into the

grade. Also, do not use the spring parking brakes

electronic control unit. Installing different sized

during freezing temperatures if the service brakes

are wet. To do so could damage the brakes if hot, or

tires could result in a reduced braking force, lead-

cause them to freeze during cold weather.

ing to longer stopping distances.

If the brakes are wet, drive the vehicle in low gear

ABS includes signal-generating tone wheels and sen-

sors located in the wheel hubs of each sensed axle.

and lightly apply the brakes to heat and dry them.

Allow hot brakes to cool before using the spring

The sensors transmit vehicle wheel speed information

to an electronic control unit (located on the frontwall).

parking brakes. Always chock the tires.

The control unit’s main circuit interprets the speed sen-

If the brakes are wet, drive the vehicle in low gear and

sor signals and calculates wheel speed, wheel retarda-

lightly apply the brakes to heat and dry them.

tion, and a vehicle reference speed. If the calculations

Allow hot brakes to cool before using the parking brake.

indicate wheel lockup, the main circuit signals the ap-

Always chock the tires.

propriate solenoid control valve to reduce braking pres-

sure. During emergency braking, the solenoid control

valve alternately reduces, increases, or maintains air

7.6

Brake System

pressure supply in the brake chamber to prevent front

valves, and the electrical circuitry. The ABS warning

and rear wheel lockup.

light comes on after turning the ignition switch to the

ON position. Once the vehicle moves faster than about

4 mph (6 km/h), the warning light goes out only if all of

CAUTION

the ABS components are working.

An accumulation of road salt, dirt, or debris on the

The Meritor WABCO^® ABS system combines one front-

ABS tone wheels and sensors can cause the ABS

axle control channel with the rear axle (the four-sensor

warning light to come on. If the ABS light does

system) to form one control circuit. For example, the

come on, the tone rings and sensors should be in-

sensor and solenoid control valve at the left-front axle

spected for corrosion and serviced if necessary.

form a control circuit with the sensor and solenoid valve

The service should include cleaning of the tone

on the right rear axle. If, during vehicle operation, the

rings and sensors. If any tone ring on a vehicle

safety circuit senses a failure in any part of the ABS

shows severe corrosion, all tone rings on that ve-

system (a sensor, solenoid control valve, wiring connec-

hicle should be replaced.

tion, short circuit, etc.), the warning light (ABS) comes

on and the control circuit where the failure occurred is

During winter months in areas where corrosive ma-

switched to normal braking action. The remaining con-

terials are used on the highways, periodically clean

trol circuit will retain the ABS effect. Even if the ABS

the underside of the vehicle, including the tone

system is partially or completely inoperative, normal

rings and sensors, to ensure proper ABS function

braking ability is maintained. An exception would be if a

and to protect the components from corrosion.

solenoid control valve (or combination solenoid control

Clean more frequently when unusually corrosive

valve) is damaged and inoperative. As these compo-

chemicals are being used.

nents are an integral part of the air brake system, nor-

mal braking may be impaired or inoperative.

IMPORTANT: During winter months in areas where

corrosive materials are used on the highways, pe-

IMPORTANT: If any of the ABS warning lights do

riodically clean the underside of the vehicle to en-

not work as described above, or come on while

sure proper ABS functioning.

driving, repair the ABS system immediately to en-

The electronic control unit also has a safety circuit that

sure full antilock braking capability.

constantly monitors the wheel sensors, solenoid control

7.7

Brake System

During emergency or reduced-traction stops, fully de-

press the brake pedal until the vehicle comes to a safe

WARNING

stop; do not pumpthe brake pedal. With the brake pedal

fully depressed, the ABS system will control all wheels

Manually adjusting an automatic slack adjuster to

to provide steering control and a reduced braking dis-

bring the pushrod stroke within legal limits is likely

tance.

masking a mechanical problem. Adjustment is not

repairing. In fact, continual adjustment of automatic

Although the ABS system improves vehicle control dur-

slack adjusters may result in premature wear of the

ing emergency braking situations, the driver still has the

adjuster itself. Further, the improper adjustment of

responsibility to change driving styles depending on the

some automatic slack adjusters may cause internal

existing traffic and road conditions. For example, the

damage to the adjuster, thereby preventing it from

ABS system cannot prevent an accident if the driver is

properly functioning.

speeding or following too closely on slippery road

surfaces.

Automatic Slack Adjusters

Automatic slack adjusters are required on all vehicles

equipped with air brakes manufactured after October

20, 1994. Automatic slack adjusters should never be

manually adjusted except during routine maintenance of

the foundation brakes (e.g., replacing shoes), during

slack adjuster installation or in an emergency situation.

When the brake pushrod stroke exceeds the legal brake

adjustment limit on a vehicle, there is likely a mechani-

cal problem with the foundation brake components or

the adjuster is improperly installed.

Visit a repair facility as soon as possible when brakes

equipped with automatic slack adjusters are determined

to be out of adjustment.

7.8

Pretrip Inspection and Daily Maintenance

inspections save time by eliminating stops later to ad-

Pretrip Inspection Checklist

just items overlooked or forgotten.

IMPORTANT: If the vehicle is taken out of service

Each checklist step corresponds with detailed instruc-

for an extended period of time (such as for the

tions found under "Pretrip Inspection and Daily Mainte-

Summer) follow the procedures below.

nance Procedures." If any system or component does

not pass this inspection, it must be corrected before

• In regions where corrosive materials are applied

operating the vehicle. See the School Bus Chassis

to roads and highways to control ice, thoroughly

Workshop Manual for repair procedures, and the School

clean the underside of the vehicle to prevent cor-

Bus Chassis Maintenance Manual for lubricant recom-

rosion.

mendations, specifications, and maintenance intervals

• Ensure that the vehicle is not parked over dry

and procedures.

brush or leaves. This is a potential fire hazard.

NOTE: Apply the parking brakes and chock the

• Disconnect the batteries and charge them peri-

tires.

odically using a trickle charger.

1. Drain the air brake system air reservoirs, if so

• Approximately once a month, connect the batter-

equipped.

ies, start the vehicle, and allow the engine to

reach normal operating temperature.

2. Inspect the batteries and battery cables.

• Once the engine reaches normal operating tem-

3. Check the fluid level in the windshield washer res-

perature, lubricate the radiator shutters. This will

ervoir.

prevent them from seizing.

4. Check the front hub lubricant level (if equipped with

The following pretrip inspection checklist helps ensure

oil-lubricated wheel bearings).

that the vehicle components are in good working condi-

5. Tilt the hood. Examine the steering components.

tion before each trip.

6. Check the coolant level in the surge tank sight

Pretrip inspections cannot be performed in a short pe-

glass and check the radiator and the charge air

riod. In checklist form, the sequence below may seem

cooler for clogging or damage. Check the radiator

to be overly time-consuming. However, careful pretrip

for coolant leaks.

8.1

Pretrip Inspection and Daily Maintenance

Check the condition and operation of the engine

check the fuel/water separator for leaks. If needed,

radiator shutters.

prime the fuel system.

Check the condition of the coolant hoses and

20.

Inspect the front and rear suspension components,

heater hoses.

including the springs and air springs, shocks, and

suspension brackets.

Check the condition of the drive belts.

21.

Check for excessive play at the steering wheel.

10.

Inspect the engine for fuel, oil, and coolant leaks.

22.

On mechanical clutch linkages (if so equipped),

11.

Inspect the engine and chassis wiring.

check the clutch pedal free-travel.

12.

Inspect the air intake system for leaks or damage.

23.

Turn the ignition switch to the ON position and start

Check the intake-air restriction indicator if it is

the engine. Be sure that the oil pressure warning

mounted on the air intake system.

system is operating. Leave the engine running.

13.

Check the fluid level in the hydraulic brake fluid res-

24.

Make sure that the electric horn is operating prop-

ervoir, if so equipped.

erly.

14.

Check the engine lubricating oil level.

25.

Make sure that all of the lights are working, includ-

15.

Check the oil level in the automatic transmission, if

ing the brake lights, high and low beam headlights,

so equipped.

turn signals, clearance lights, and emergency flash-

ers. Check the condition of the reflectors. Turn the

16.

Check the fuel water separator (if so equipped) for

lights off. Shut down the engine.

contaminants.

26.

Inspect the air brake components (if so equipped)

17.

Close the hood and engage the hood hold-down

including the brake chamber pushrods, air reser-

latches.

voirs, and air lines.

18.

Inspect the fuel tank(s) and fuel line connections. If

27.

Check the brake lining wear (if equipped with air

so equipped, be sure that the fuel tank shutoff

brakes).

valves are open.

28.

Make sure that the brakes are adjusted on all ax-

19.

Check the fuel level in the fuel tank(s) and be sure

les.

that the fuel cap vent area is clean. If so equipped,

8.2

Pretrip Inspection and Daily Maintenance

29. Check the tire inflation pressures and inspect each

After the water and oil condense, they collect near

tire for bulges, cracks, cuts, and punctures.

the tank drain valves. Drain the resulting emulsion

as follows:

30. Check for indications of loose wheel nuts or rim

nuts and examine each rim and wheel component.

WARNING

31. Check the air brake system for proper operation.

32. Test the service brakes before leaving the lot.

Failure to drain the air reservoirs as instructed

could cause sludge formation in the air brake sys-

33. Test the parking brakes on a 20-percent grade.

tem. Sludge could adversely affect braking, causing

loss of control, which could cause death, personal

Pretrip Inspection and Daily

injury, or property damage.

Maintenance Procedures

IMPORTANT: If the air tanks are not equipped

Whenever equipment requires adjustment, replacement,

with automatic drain valves, they must be

repair, addition of lubricants, or a change of lubricants,

drained daily. If they are equipped with auto-

see the School Bus Chassis Workshop Manual for re-

matic drain valves, they must be drained in

pair procedures and specifications. See the School Bus

this same manner at least once a week.

Chassis Maintenance Manual for lubricant recommen-

1.1

Open the wet tank valve (the drain cock or

dations, specifications, and maintenance intervals and

pull-chain drain located on the forward end

procedures.

of the supply air reservoir, which is con-

1. Drain the air brake system air reservoirs, if so

nected directly to the air compressor). Block

equipped.

the valve open.

Air reservoirs serve as storage tanks for com-

pressed air. They collect water condensed from the

WARNING

air and small amounts of oil from the air compres-

sor. Water and oil normally enter the reservoir in

When draining the air reservoir, do not look into the

the form of vapor because of the heat generated

air jets or direct them toward anyone. Dirt or sludge

during compression.

8.3

Pretrip Inspection and Daily Maintenance

particles may be in the airstream and could cause

injury.

CAUTION

1.2

Exhaust the remaining air and moisture from

Take care to keep the vent plugs tight so that the

the system by opening the drain cocks on

neutralizing solution does not enter any of the bat-

the bottoms of the remaining air reservoirs.

tery cells and damage the battery.

Block the valves open.

2.2

Remove any corrosion from the hold down

1.3

Water and oil emulsion often forms pockets

and the top of the battery. Use diluted am-

which will not drain while compressed air is

monia or a soda solution to neutralize the

in the reservoirs. Because of these pockets,

acid present, then rinse off the ammonia or

leave the valves blocked open during the

soda solution with clean water.

first part of the pretrip inspection.

If the battery posts or cable terminals are

2. Inspect the batteries and battery cables as follows:

corroded, disconnect the terminals from the

posts. Clean them with a soda solution and

WARNING

a wire brush. After cleaning, connect the ter-

minals to the battery posts, then apply a thin

Battery posts, terminals, and related accessories

coat of petroleum jelly to the posts and ter-

contain lead and lead compounds, chemicals

minals to help retard corrosion.

known to the State of California to cause cancer

3. Check the fluid level in the windshield washer res-

and reproductive harm. To prevent possible per-

ervoir.

sonal injury, always wash your hands after handling

battery parts and related accessories.

Tilt the hood to access the reservoir (located next

2.1

Access the batteries. Be sure that the bat-

to the surge tank). Add washer fluid as needed.

tery hold down is secure. If it is loose,

See Fig. 8.1.

tighten the hold-down bolts; if it is broken,

replace it.

8.4

Pretrip Inspection and Daily Maintenance

burning material, such as a cigarette. Always com-

ply with the washer fluid manufacturer’s recom-

mended safety precautions.

4. Check the front hub lubricant level (if equipped with

oil-lubricated wheel bearings).

Observe the level of the wheel bearing lubricant in

the hub cap at each end of the front axle and, if

needed, fill the hubs to the level indicated on the

hub cap. See Group 33 of the School Bus Chassis

Maintenance Manual for recommended lubricants.

IMPORTANT: Before removing the fill plug, always

clean the hub cap and plug.

5. Tilt the hood. Examine the steering components.

Examine the steering gear mounting bolts, pitman

arm nut, and the drag link nuts for tightness. See

07/30/96

f500273

Fig. 8.2. Be sure that the steering driveline and the

1. Windshield Washer Reservoir

U-joints are in roadworthy condition, without cracks,

2. Surge Tank

breaks, looseness, or other damage. Tighten loose

3. Sight Glass

nuts, and replace damaged parts as needed. For

instructions, see Group 46 of the School Bus

Fig. 8.1, Check the Surge Tank Fluid Level

Chassis Workshop Manual.

WARNING

Washer fluids may be flammable and poisonous. Do

not expose washer fluid to an open flame or any

8.5

Pretrip Inspection and Daily Maintenance

CAUTION

Coolant must be filled to the full line of the surge

tank. Low coolant could result in engine overheat-

ing, which could cause engine damage.

6. Check the coolant level in the surge tank sight

glass. See Fig. 8.1. Check the condition of the ra-

diator fins and the charge air cooler.

If the coolant level is low, check the amount of anti-

freeze protection. If the protection is adequate, add

a 50/50 mixture of water and antifreeze. If addi-

tional protection is needed, add antifreeze only. Fill

to the level of the bottom of the surge tank fill neck.

Good airflow through the radiator core and air-to-air

aftercooler core is essential for proper engine cool-

ing. The cores allow air passage, but form a particle

barrier which tends to collect insects and airborne

debris.

10/05/94

f460512b

Inspect for clogged fins. Use compressed air or wa-

1. Steering Gear Mounting Bolt

ter directed from the fan side of the core to back-

2. Pitman Arm Pinch Bolt Nut

flush any material restricting airflow.

Fig. 8.2, Steering Gear (TAS series)

Inspect and clean the charge air cooler. If clogged,

the airflow through the radiator could be restricted.

Straighten bent or damaged fins to permit airflow

across all areas of the cores.

8.6

Pretrip Inspection and Daily Maintenance

Repair or replace the radiator if it is leaking. See

Tighten hose clamps as necessary, but do not over-

Group 20 of the School Bus Chassis Workshop

tighten as hose life can be adversely affected.

Manual for instructions.

Be sure that the hose support brackets are securely

NOTE: When traveling through areas of high in-

fastened. Make sure that the hoses are not located

sect concentrations, it may be necessary to clean

near sources of wear, abrasion, or high heat.

the exterior of the radiator or aftercooler core as

9. Check the condition of the drive belts.

often as every 200 miles (320 km).

Check the fan belt(s) and the alternator belt for

7. Check the condition and operation of the engine

signs of glazing, wear (frayed edges), damage

radiator shutters.

(breaks or cracks), or oil contamination. If a belt is

glazed, worn, damaged, or oil soaked, replace the

Inspect both pneumatic- and hydraulic-type engine

belt following the instructions in Group 01 of the

radiator shutters and ensure that they are free of

School Bus Chassis Workshop Manual.

contaminants and corrosion and operate properly.

8. Check the condition of the coolant hoses and

Check all of the belts for proper tension. See

heater hoses.

Group 01 of the School Bus Chassis Workshop

Manual for instructions.

Make sure that the radiator inlet and outlet coolant

hoses and heater hoses are pliable and are not

NOTE: On Cummins engines, a belt tensioner au-

cracking or ballooning. Replace hoses that show

tomatically adjusts the fan and alternator belt to

signs of cracking, weakening, or ballooning. Re-

the correct tension. If the belt slips, repair or re-

place all hoses, including heater hoses, at the

place the tensioner. For instructions, see the Cum-

same time. Service-type knitted or braided yarn-

mins Engine Operation and Maintenance Manual.

reinforced neoprene hose is acceptable.

10. Inspect the engine for fuel, oil, and coolant leaks.

Silicone hoses, having an extended service life, can

Correct any leaks found.

be substituted for the reinforced neoprene type.

See the Service Parts Catalog or contact your

11. Inspect the engine and chassis wiring.

dealer.

8.7

Pretrip Inspection and Daily Maintenance

Inspect the engine and chassis for loose wiring,

13. Check the fluid level in the hydraulic brake fluid res-

chafed insulation, and damaged or loose hold-down

ervoir, if so equipped. See Fig. 8.3.

clamps. Tighten loose wires or hold-down clamps;

If needed, fill the reservoir up to the ridge that sur-

replace damaged wiring or clamps.

rounds the reservoir. Use only heavy-duty brake

12. Check the air intake system for leaks or damage.

fluid, DOT 3.

Check the intake-air restriction indicator to deter-

mine if the air cleaner filter element needs to be

changed. Replace the filter element if the yellow

signal stays locked at 25 inH₂0. See Group 09 of

the School Bus Chassis Workshop Manual for filter

element replacement instructions.

Check the engine air intake piping from the air

cleaner to the engine intake. Inspect the piping for

loose connections, cracks, torn or collapsed hoses,

punctures, and other damage. Tighten loose con-

nections and replace damaged components. Make

sure that the piping system is airtight so that all of

the intake air passes through the air cleaner.

CAUTION

Failure to maintain a sealed air intake system could

10/31/94

f460513a

allow the entry of dirt and contaminants into the

A. Open caps and check fluid level.

engine. This could adversely affect engine perfor-

B. Fill to this level.

mance and result in engine damage.

Fig. 8.3, Check the Hydraulic Brake Fluid Level

NOTE: After replacing the filter element, reset the

restriction indicator by pressing the reset button.

8.8

Pretrip Inspection and Daily Maintenance

14.

Check the engine oil level. See Fig. 8.4.

CAUTION

The oil level should show between the upper and

lower marks on the dipstick. Add enough oil to bring

Operating the engine with the oil level below the

the level up to the operating range. See the engine

low mark or above the high mark could result in en-

manufacturer’s Operation and Maintenance Manual

gine damage.

for recommended lubricants and capacities.

15. Check the oil level in the automatic transmission, if

so equipped.

NOTE: The fluid must be warm to ensure an accu-

rate check. The fluid level rises as temperature in-

creases.

With the vehicle on a level surface, check the oil

level (the dipstick is next to the windshield washer

reservoir) in the transmission using one of the fol-

lowing procedures:

Hot Check

• Operate the transmission in a Drive (D)

range until normal operating temperature,

160 to 200°F (71 to 93°C), is reached.

• Park the vehicle. Shift to Neutral (N) and ap-

ply the parking brake. Let the engine run at

idle.

f010346

• Wipe the dipstick clean and check the fluid

Fig. 8.4, Check the Engine Oil Level

level. A safe operating level is any level

within the HOT run (upper) band on the dip-

stick. See Fig. 8.5.

8.9

Pretrip Inspection and Daily Maintenance

• If the fluid is not within this range, add or

• With the engine running, wipe the dipstick clean

drain fluid as needed to bring the level to the

and check the fluid level. See Fig. 8.5. Any level

top of the HOT run band. See the School

within the COLD run (lower) band is satisfactory

Bus Chassis Maintenance Manual for fluid

for operating the vehicle. If the level is not within

types and capacities.

the COLD run band, add or drain fluid until it

reaches the middle of the COLD run band.

• Perform a hot check at the first opportunity after

normal operating temperature, 160 to 200°F (71

to 93°C), is reached.

16.

Check the fuel water separator (if so equipped) for

contaminants.

With the engine shut down, partially open the drain

valve under the collection bowl and drain water and

contaminants as needed.

17.

Close the hood and engage the hood hold-down

latches.

02/27/2002

f270077

18.

Inspect the fuel tank(s) and fuel line connections. If

A. HOT Run Band

so equipped, be sure that the fuel tank shutoff

B. COLD Run Band

valves are open.

Fig. 8.5, Automatic Transmission Dipstick

Replace leaking fuel tanks. Repair or replace any

lines or connections that are leaking. For proce-

Cold Check

dures, see Group 47 of the School Bus Chassis

Workshop Manual.

• A cold check may be made when the sump tem-

perature is 60 to 104°F (15 to 40°C).

If equipped with fuel tank shutoff valves, be sure

• Run the engine for at least one minute to clear

that the valves are fully open.

the fluid system of air.

8.10

Pretrip Inspection and Daily Maintenance

19.1

To keep condensation to a minimum, fill the

CAUTION

fuel tanks at the end of each day, but not to

more than 95 percent of liquid capacity. Se-

Never operate the engine with the fuel tank shutoff

lect the proper grade of fuel as specified by

valves partly closed. This could damage the fuel

the engine manufacturer.

pump, causing a sudden loss of engine power.

19. Check the fuel level in the tank(s) and be sure that

WARNING

the fuel cap vent area is clean. Check the fuel/

water separator (if so equipped) for leaks, and if

Do not mix gasoline or alcohol with diesel fuel. This

needed, prime the fuel tank system.

mixture could cause an explosion. When filling fuel

tanks, do not smoke or use an open flame near the

fuel tanks. Combustion of diesel fuel oil or fuel va-

WARNING

pors could result, possibly causing personal injury

or property damage.

Never fill fuel tanks to more than 95 percent of their

liquid capacity. This could make them more likely to

19.2

Always strain or filter fuel before filling the

rupture from impact, possibly causing fire and re-

tanks. This will lengthen the life of the en-

sulting in serious personal injury or death by burn-

gine fuel filter and reduce the chances of dirt

ing.

entering the engine.

20. Inspect the front and rear suspension components,

IMPORTANT: Use only low-sulfur diesel fuels.

including the springs and air springs, shocks, and

Low-sulfur diesel fuels have a maximum 0.05

suspension brackets.

percent sulfur content compared to a 0.26 to

0.30 percent sulfur content for other fuels. Fail-

Check for broken spring leaves, loose U-bolts,

ure to use low-sulfur diesel fuels may void the

cracks in the suspension brackets, and loose fas-

warranty on emissions components.

teners in the spring hangers and shackles. Inspect

the shock absorbers for loose fasteners and leaks.

Tighten all loose fasteners and replace any compo-

nent that is worn, cracked, or otherwise damaged.

8.11

Pretrip Inspection and Daily Maintenance

justment of the linkage and steering gear before

WARNING

operating the vehicle.

Do not replace individual leaves of a damaged front

or rear suspension leaf spring assembly; replace

the complete spring assembly. Visible damage,

such as cracks or breaks, to one leaf causes hidden

damage to other leaves. Replacement of only the

visibly damaged part(s) is no assurance that the

spring is safe. If cracks or breaks exist on front

spring assemblies in either of the two top leaves, a

loss of vehicle control could occur. Failure to re-

place a damaged spring assembly could cause an

accident resulting in serious personal injury or

property damage.

21. Check the steering wheel for excessive play.

11/15/2000

f460158c

A. Lash Area

With the front tires pointing straight ahead, turn the

steering wheel until motion is observed at the front

Fig. 8.6, Measure Lash at the Steering Wheel

wheels. Align a reference mark on a ruler, then

slowly turn the steering wheel in the opposite direc-

22. Check the clutch pedal free-travel, if applicable.

tion until motion is again detected at the wheels.

Measure the lash (free play) at the rim of the steer-

The main indicator for assessing clutch wear is

ing wheel. See Fig. 8.6.

clutch pedal free-travel. Free-travel is a decreased

resistance felt at the top of the clutch pedal stroke.

Excessive lash exists if steering wheel movement

With the clutch pedal in this range, the clutch is

exceeds 4-3/4 inches (121 mm) with an 18-inch

fully engaged and the only resistance to clutch

(470-mm) steering wheel. If there is excessive lash,

pedal movement is return spring tension. Clutch

check the steering system for wear or incorrect ad-

pedal free-travel should be approximately 1-1/2 to 2

inches (38 to 51 mm). See Fig. 8.7. If the clutch

8.12

Pretrip Inspection and Daily Maintenance

pedal free-travel is less than 3/4 inch (19 mm), ad-

just the clutch internally.

For instructions, see Group 25 of the School Bus

Chassis Workshop Manual.

CAUTION

Excessive clutch free pedal may prevent complete

clutch disengagement; insufficient clutch pedal

free-travel causes slippage and short clutch life.

Never wait for the clutch to slip before making a

clutch adjustment.

23. Start the engine and make sure that the oil-

pressure warning system is working.

When the engine is started, the oil-pressure warn-

ing will come on until the oil pressure rises above a

preset minimum.

If the warning does not come on when the ignition

switch is turned to the ON position, repair the sys-

tem.

09/06/96

f250344

A. About 1-1/2 to 2 inches (38 to 51 mm)

CAUTION

Fig. 8.7, Check Clutch Pedal Free-Travel

Failure to repair the engine shutdown/ warning sys-

tem could result in a sudden engine shutdown with-

24. Make sure that the electric horn works.

out warning during vehicle operation.

25. Make sure that all of the lights are working.

8.13

Pretrip Inspection and Daily Maintenance

Turn on the headlights, dash lights, and emergency

handling and may lead to loss of vehicle control

flashers and leave them on.

resulting in property damage or personal injury.

If any of the gauge bulbs, the switch panel label

bulb, or the right- and left-turn indicator bulbs are

CAUTION

not working, replace them. If they still don’t work,

find and correct the problem. Turn off all of the

If the external breather tube or breather cap is miss-

lights. Shut down the engine.

ing or incorrectly installed, road dirt and debris can

adversely affect the operation of the brake chamber.

Once inside of the chamber, dirt and debris can

DANGER

cause the internal parts of the chamber to deterio-

rate faster.

Do not loosen or remove the parking brake clamp

ring for any purpose. See Fig. 8.8. The parking/

NOTE: Check vehicles operating under severe or

emergency brake section of the brake chamber is

adverse conditions more frequently.

not intended to be serviced. Serious injury or death

26. Inspect the air brake components (if so equipped)

may result from sudden release of the power

including the brake chamber pushrods, air reser-

spring.

voirs, and air lines.

Before doing any repairs or adjustments on a

Look for worn clevis pins on brake chamber push-

service/parking brake chamber, read the applicable

rods and missing or damaged cotter keys on the

warnings and instructions in Group 42 of the School

brake chamber pushrod clevis pins. Replace worn

Bus Chassis Workshop Manual.

clevis pins and install new cotter keys if necessary.

WARNING

Visually inspect the piston rod engagement with the

clevis. At least seven threads of engagement are

required; there should be 1 inch (25 mm) of clear-

Do not operate the vehicle with the front brakes

ance from the center line of the clevis pin hole to

backed off or disconnected. Backing off or discon-

the end of the piston rod. See Fig. 8.9. See Group

necting the front brakes will not improve vehicle

42 of the School Bus Chassis Workshop Manual for

adjustment procedures.

8.14

Pretrip Inspection and Daily Maintenance

See if the chamber piston rod is in line with the

with new ones. Do not repair damaged reservoirs.

slack adjuster. Misalignment can cause the piston

Old or used reservoirs are not acceptable as re-

rod to rub on the nonpressure chamber and cause

placements. If a reservoir requires replacement,

a dragging brake. See Group 42 of the School Bus

see Group 42 of the School Bus Chassis Work-

Chassis Workshop Manual if the chamber piston

shop Manual for instructions.

rod is improperly aligned.

Inspect the air lines as follows:

Visually inspect the exterior surfaces of the cham-

26.1

Check the clearance between the hoses,

ber for damage. Make sure that breather holes in

exhaust manifold, and turbocharger, or other

the nonpressure section(s) are open and free of

hot spots. Excessive heat will cause the ma-

debris. See Group 42 of the School Bus Chassis

terial in the hoses to deteriorate rapidly or

Workshop Manual for instructions to replace dam-

become brittle. Provide at least six inches

aged parts.

(150 mm) of clearance. More clearance is

On all parking brake installations, check for the

recommended if the hose is located above

presence of an end cover cap or dust plug and

the heat source.

make sure that the cap or plug is securely snapped

26.2

Check for kinks, dents, or swelling of the

into place. On most MGM parking brake chambers

hoses. If a hose is damaged, replace it with

equipped with an integral release bolt, an end cover

one of the same size and type.

cap is installed over the release bolt. Be sure that

the end cover cap is snapped tightly into place.

26.3

Do not route the hose on top of anything

likely to be stepped on or walked on.

Check for rusted connections, missing snap rings,

26.4

Check for damage to hoses located near

and damaged camshaft grease seals. Repair or

moving parts, such as drivelines, suspen-

replace damaged or missing parts.

sions, and axles. If the moving parts are

Check the air reservoir band fasteners. Make sure

catching or pinching the lines, make correc-

that the outside surfaces of the reservoirs are

tions as needed.

painted to prevent corrosion damage. Inspect the

reservoir surfaces for damage, such as cracks and

dents. Replace corroded or damaged reservoirs

8.15

Pretrip Inspection and Daily Maintenance

26.5

Check for hose damage caused by abrasion.

26.8

Inspect air tubing, especially tubing made of

If a hose is abraded, replace it. Check for

nylon. In cold weather, nylon tubing is sensi-

the cause of the abrasion, such as loose or

tive to damage, such as nicks or cuts. Re-

damaged hose clamps. Repair or replace

place nicked or cut tubing, even if it is not

the clamps as needed.

leaking.

26.6

Observe the hose cover condition, especially

26.9

Check the bend radii of all hoses. See

hoses exposed to water splash and ice. If

Fig. 8.10. The minimum bend radius of a

any hose is dried out or ragged (the wire or

hose is that bend which the hose will with-

liner is showing through the cover), replace

stand without experiencing damaging

the hose.

stresses or kinking. For minimum bend ra-

dius values, see Group 42 of the School

26.7

Inspect the front air brake lines for leaks at

Bus Chassis Workshop Manual.

the fitting where they enter the air chamber.

When a rubber hose bend does not meet

With an assistant at the front wheels to in-

minimum radius requirements, the outside

spect the brake lines, turn the wheels to full

may appear smooth even if the inner tube is

lock in one direction. While holding the ser-

kinked. Reroute the hose or replace it with

vice brake pedal down, inspect the front

one of adequate length if the bend radius is

brake air lines closely where they enter the

not within minimum specifications.

air chambers.

26.10

Check straight hose installations (those

Turn the wheels to full lock in the other di-

hoses that do not bend along their routings).

rection, hold the service brake pedal down,

Pressure changes can cause a hose to

and repeat the inspection.

lengthen up to two percent, or shorten up to

four percent. A 100-inch (2540-mm) length of

If there is a leak, the hose should be re-

hose, for example, can contract to 96 inches

placed.See Group 42 of the School Bus

(2440 mm). If the hose has no slack when it

Chassis Workshop Manual for the hose re-

is exhausted of air, replace it with one of

placement procedure.

adequate length to avoid a possible blow-off

from the fitting during vehicle operation.

8.17

Pretrip Inspection and Daily Maintenance

27.2

If the axle assembly is not equipped with a

dust shield or backing plate, measure the

axle brake lining thickness. If any of the

brake linings are worn to less than 1/4 inch

(6.5 mm) at the thinnest point, replace the

linings on all brake assemblies on that axle.

See Group 42 of the School Bus Chassis

Workshop Manual for lining replacement in-

structions and camshaft endplay inspection.

11/03/94

f420329a

27.3

If the axle assembly is equipped with a dust

NOTE: The center of the hose bend radius should be

shield or backing plate, remove the inspec-

well away from the fitting.

tion plugs to inspect the brake lining thick-

A. Bend Radius

ness. If any of the brake linings are worn to

less than approximately 1/4 inch at the thin-

Fig. 8.10, Bend Radius

nest point, replace the linings on all brake

assemblies on that axle. See Group 42 of

26.11

Check for kinked or twisted hoses. A seven-

the School Bus Chassis Workshop Manual

percent twist in the hose can reduce its life

for lining replacement instructions and cam-

by up to 90 percent. Also, a twisted hose

shaft endplay inspection.

under pressure tends to untwist. This could

cause it to loosen the fitting. Reconnect

27.4

Install the inspection plugs in the dust

hoses that are twisted.

shields or backing plates, if so equipped.

27. Check the brake lining wear on vehicles equipped

27.5

Remove the chocks from the tires.

with air brakes. Proper brake operation is depen-

28.

Make sure that the brakes are adjusted on all ax-

dant on periodic maintenance and inspection of the

les.

brake linings.

Adjust the brakes if necessary. See Group 42 of

27.1

Set the parking brake, and chock the tires to

the School Bus Chassis Maintenance Manual for

prevent vehicle movement.

checking and adjusting procedures.

8.18

Pretrip Inspection and Daily Maintenance

IMPORTANT: Brake checking and adjusting is nec-

See the tire manufacturer’s recommenda-

essary for all vehicles, including those equipped

tions for the correct tire inflation pressures

for the vehicle load.

with automatic slack adjusters.

29. Check the tire inflation pressures and inspect each

Overinflation gives the treaded surface of

tire for bulges, cracks, cuts, and punctures.

the tire a convex shape. See Fig. 8.12. This

causes extreme tire wear in the middle part

IMPORTANT: The load and cold inflation pres-

of the tire since this section is primarily in

sure must not exceed the rim or wheel manu-

contact with the road.

facturer’s recommendations, even though the

Underinflation gives the tread surface a con-

tire may be approved for a higher load or infla-

cave shape. See Fig. 8.12. This causes ex-

tion. Some rims and wheels are stamped with

cessive tire wear on the outer edges of the

a maximum load and maximum cold inflation

tire since they are primarily in contact with

rating. See Group 40 of the School Bus Chas-

the road.

sis Workshop Manual for the correct tire infla-

tion pressure for the vehicle load or consult

WARNING

the rim or wheel manufacturer if they are not

stamped. If the load exceeds the maximum rim

Do not operate the vehicle with underinflated or

or wheel capacity, the load must be adjusted

overinflated tires. Incorrect inflation can stress the

or reduced.

tires and make the tires and rims more susceptible

to damage, possibly leading to rim or tire failure

29.1

Check the inflation pressures of the tires be-

and loss of vehicle control, resulting in serious per-

fore each trip using an accurate tire pres-

sonal injury or death.

sure gauge. See Fig. 8.11. Check the tires

when cool. Be sure that valve stem caps are

29.2

If a tire has been run flat or underinflated,

on every tire and that they are screwed on

check the wheel for proper lockring and side

finger-tight. Inflate the tires to the correct

ring seating, and possible wheel, rim, or tire

pressures if needed.

damage before adding air.

8.19

Pretrip Inspection and Daily Maintenance

11/03/94

f400062a

A. Tire correctly inflated.

B. Tire overinflated.

C. Tire underinflated.

Fig. 8.12, Check for Proper Tire Inflation

pressure loss of 4 psi (28 kPa) or more in a

tire may indicate damage. Inspect and repair

or replace the tire.

11/03/94

f400061

29.5

If the tires are wearing irregularly, rotate

Fig. 8.11, Check Tire Inflation Pressures

them. If the front steering axle tires become

irregularly worn, move them to the drive

29.3

Moisture inside a tire can result in body ply

axle. See Fig. 8.13. Have the front axle

separation or a sidewall rupture. During tire

alignment checked to determine the cause

inflation, compressed air reservoirs and lines

of irregular tire wear. In a dual assembly, if

must be kept dry. Use well-maintained inline

one tire wears faster than its mate, reverse

moisture traps and service them regularly.

the position of the two tires. See Fig. 8.14.

29.4

Inspect the tires for bulges, cracks, cuts, or

Government regulations require the removal

penetrations. A tire pressure check will assist

of front axle tires at 4/32-inch (3-mm) re-

in uncovering hidden damage. A weekly

maining tread depth and rear axle tires at

8.20

Pretrip Inspection and Daily Maintenance

2/32-inch (1.5-mm) remaining tread depth.

However, front axle tires may be rotated to

the drive axles to use the remaining 2/32-

inch (1.5-mm) tread rubber.

See Group 40 of the School Bus Chassis

Workshop Manual for additional information

on tire matching, spacing of dual tires, and

07/25/96

f400116

causes of abnormal tire wear.

Fig. 8.14, Dual Assembly Rotation

Check the wheel nuts or rim nuts for indications of

looseness. Remove all dirt and foreign material

from the assembly. Dirt or rust streaks from the

stud holes, metal buildup around stud holes, or out-

of-round or worn stud holes, may be caused by

loose wheel nuts. See the School Bus Chassis

Maintenance Manual for torque specifications and

the correct tightening sequences.

Examine the wheel assembly components (includ-

07/25/96

f400115

ing rims, rings, flanges, studs, and nuts) for cracks

or other damage.

Fig. 8.13, Front Axle to Rear Axle Rotation

See Group 33 and Group 35 of the School Bus

29.6

Also inspect tires for oil contamination. Fuel

Chassis Workshop Manual for service procedures

oil, gasoline, and other petroleum deriva-

for the studs and hubs, and Group 40 of the

tives, if allowed to contact the tires, will

School Bus Chassis Workshop Manual for wheel

soften the rubber and destroy the tire.

and tire servicing. Replace broken, cracked, badly

30. Check for indications of loose wheel nuts or rim

worn, bent, rusty, or sprung rings and rims. Be sure

nuts and examine each wheel component.

8.21

Pretrip Inspection and Daily Maintenance

that the rim base, lockring, and side ring are

should cut out the air compressor at approxi-

matched according to size and type.

mately 125 psi (862 kPa). With the engine

idling, make a series of foot valve applica-

tions. The air governor should cut in the air

WARNING

compressor at approximately 95 psi (655

kPa). If the air governor does not cut in and

Have any worn or damaged wheel components re-

out as described above, adjust it to these

placed by a qualified person using the wheel manu-

specifications. If the air governor cannot be

facturer’s instructions and the wheel industry’s

adjusted or repaired, replace it before oper-

standard safety precautions and equipment. Other-

ating the vehicle.

wise a vehicle or workshop accident could occur,

possibly resulting in serious personal injury or

31.2

Check the air pressure buildup time as fol-

death.

lows:

Release the parking brake by pushing in the

CAUTION

parking brake control valve knob.

With the air system fully charged to 125 psi

Insufficient wheel nut (rim nut) torque can cause

(862 kPa), make one full brake application

wheel shimmy, resulting in wheel damage, stud

and note the air pressure reading on the

breakage, and extreme tire tread wear. Excessive

gauge. Continue to reduce the air pressure

wheel nut torque can break studs, damage threads,

by moderate brake applications to a maxi-

and crack discs in the stud hole area. Use the rec-

mum of 90 psi (620 kPa), then run the en-

ommended torque values and follow the proper

gine at governed rpm. If the time required to

tightening sequence.

raise the air pressure to 125 psi (862 kPa) is

31. Check air brake system components for correct op-

more than 30 seconds, eliminate any leaks

eration as follows:

or replace the air compressor before operat-

31.1

Release the parking brake by pushing in the

ing the vehicle.

parking brake control valve knob. Check the

31.3

Check the air pressure reserve. With the air

air governor cut-in and cut-out pressures.

system fully charged to 125 psi (862 kPa),

Run the engine at fast idle. The air governor

stop the engine and note the air pressure.

8.22

Pretrip Inspection and Daily Maintenance

Then make one full brake application and

one minute and note the air pressure gauge

observe the pressure drop. If it drops more

reading. Observe the air pressure drop in psi

than 25 psi (172 kPa), all areas of leakage

(kPa) per minute.

must be eliminated before operating the ve-

If leakage exceeds the limits shown in

hicle.

Table 8.1, repair all areas of leakage before

driving the vehicle.

WARNING

Maximum Allowable Service Brake Air Leakage in psi

Before operating the vehicle, be sure that the park-

(kPa) Per Minute

ing brake passes the following tests. Otherwise an

Released

Applied

unexpected parking brake application could occur,

(14)

(21)

causing some loss of vehicle control and possibly

resulting in serious personal injury.

Table 8.1, Maximum Allowable Service Brake Air

Leakage

31.4

Check the air leakage in the system.

32. Test the service brakes before leaving the lot.

With the parking brake applied, the transmis-

sion out of gear, and the tires chocked,

Depress the brake pedal, release the parking

charge the air system until a cutoff pressure

brake, and check that the brake system warning

of 125 psi (862 kPa) is reached.

light goes out. If the warning light remains on after

releasing the parking brake, correct the problem

With the service brakes released, shut down

before driving off.

the engine, wait one minute and note the air

pressure gauge reading. Observe the air

If equipped with air brakes, test the brakes (when

pressure drop in psi (kPa) per minute.

starting to move the vehicle and before picking up

speed) with the foot valve and parking brake valve

Charge the air system until a cutoff pressure

to be sure that they will bring the vehicle to a safe

of 125 psi (862 kPa) is reached. With the

stop.

parking brake released and the service

brake applied, shut down the engine, wait

33. Test the parking brakes on a 20-percent grade.

8.23

In an Emergency

Hazard Warning Lights

Towing

The hazard warning light tab is located on the turn sig-

nal lever. See Fig. 9.1. To operate the hazard lights,

WARNING

pull the tab out. All of the turn signal lights and both of

the indicator lights on the control panel will flash.

Do not tow an unbraked vehicle if the combined

weight of both vehicles is more than the sum of the

Push the tab in to cancel the hazard warning lights.

gross axle weight ratings (GAWR) of the towing ve-

hicle. Otherwise brake capacity will be inadequate,

which could result in personal injury or death.

IMPORTANT: When it is necessary to tow the ve-

hicle, follow the instructions below closely to pre-

vent damage to the vehicle.

When towing or pushing any vehicle equipped with

an Allison transmission, disconnect the driveshaft

at the rear axle and support it as necessary, re-

gardless of the distance or speed traveled.

07/09/96

f461080

Front Towing Hookup

1. Turn Signal Lever

2. Hazard Warning Light Tab

1. Disconnect the battery ground cable.

Fig. 9.1, Hazard Warning Light Tab

2. If the vehicle is to be lifted and towed, remove the

driveaxle shafts.

9.1

In an Emergency

6. Connect the clearance lights, taillights, and signal

CAUTION

lights. Connect any special towing lights required by

local regulations.

Failure to remove the axle shafts when towing the

vehicle with the rear wheels on the ground could

WARNING

result in damage to the transmission and other

parts.

Before releasing the parking brakes, make the con-

3. Cover the ends of the hubs with metal plates or

nection to the towing vehicle or chock the tires on

plywood cut to fit the axle opening and drilled to fit

the disabled vehicle. Failure to do so could result in

the axle shaft studs. This prevents lubricant from

hazardous conditions because the vehicle could

leaking out, and will keep contaminants from getting

suddenly roll and injury could occur.

into the axle lubricant and damaging the wheel

bearings.

CAUTION

WARNING

Before attempting to tow a vehicle with an air sus-

pension (and during the towing operation), ensure

Due to the many variables that exist in towing, posi-

that the air suspension is properly charged. Charge

tioning the lifting and towing device is the sole re-

the suspension through the Schrader valve on the

sponsibility of the tow vehicle operator. The opera-

air dryer. Attempting to tow a vehicle with an im-

tor must be familiar with standard towing industry

properly charged air suspension may result in dam-

safety measures. Improper procedures could result

age to the chassis and body.

in personal injury or death.

7. Release the parking brake.

4. Attach the towing device.

5. Lift the vehicle, and secure the safety towing

Rear Towing Hookup

chains. If additional clearance is needed, remove

1. Position the front tires so that they point straight

the front wheels.

ahead and secure the steering wheel in this posi-

tion.

9.2

In an Emergency

2. Disconnect the battery ground cable.

Emergency Starting With

Jumper Cables

WARNING

When using jumper cables, follow the instructions

Due to the many variables that exist in towing, posi-

below.

tioning the lifting and towing device is the sole re-

sponsibility of the tow vehicle operator. The opera-

WARNING

tor must be familiar with standard towing industry

safety measures. Improper procedures could result

Batteries release explosive gas. Do not smoke when

in personal injury or death.

working around batteries. Put out all flames and re-

3. Attach the towing device.

move all sources of sparks or intense heat in the

4. Lift the vehicle, and secure the safety towing

vicinity of the battery. Do not allow the vehicles to

touch each other. Do not lean over the batteries

chains.

when making connections, and keep all other per-

5. Connect the clearance lights, taillights, and signal

sons away from the batteries. Failure to follow

lights. Also connect any special towing lights re-

these precautions could lead to severe personal in-

quired by local regulations.

jury as a result of an explosion or acid burns.

CAUTION

Before attempting to tow a vehicle with an air sus-

Make sure both starting systems have the same

pension (and during the towing operation), ensure

voltage outputs, and avoid making sparks. Other-

that the air suspension is properly charged. Charge

wise the vehicle charging systems could be se-

the suspension through the Schrader valve on the

verely damaged. Also, do not attempt to charge iso-

air dryer. Attempting to tow a vehicle with an im-

lated, deep-cycle batteries with jumper cables.

properly charged air suspension may result in dam-

Follow the manufacturer’s instructions when charg-

age to the chassis and body.

ing deep-cycle batteries.

9.3

In an Emergency

1. Set the parking brake and turn off the lights and all

other electrical loads.

2. Connect one end of a jumper cable to the positive

terminal of the booster battery, and connect the

other end of the cable to the positive terminal of the

discharged battery. See Fig. 9.2.

WARNING

Do the next step exactly as instructed and do not

allow the clamps of one cable to touch the clamps

of the other cable. Otherwise, a spark could occur

near a battery, possibly resulting in severe personal

injury from explosion and acid burns.

3. Connect one end of the second jumper cable to the

negative terminal of the booster battery, and con-

nect the other end of the cable to a ground at least

12 inches (300 mm) away from the batteries of the

08/21/96

f541286

vehicle needing the start. The vehicle frame is usu-

1st

3rd

ally a good ground. Do not connect the cable to or

2nd

D. To Frame (ground)

near the discharged batteries.

Booster Battery

2. Discharged Battery

4. Start the engine of the vehicle with the booster bat-

Fig. 9.2, Jumper Connections

teries, and let the engine run for a few minutes to

charge the batteries of the other vehicle.

CAUTION

Don’t crank the engine for more than 30 seconds at

a time during any of the following procedures. Wait

9.4

In an Emergency

two minutes after each try to allow the starter to

fuel tanks. Combustion of diesel fuel oil or fuel va-

cool. Failure to do so could cause starter damage.

pors could result, possibly causing personal injury

or property damage.

5. Attempt to start the engine of the vehicle with the

batteries receiving the charge.

1. If possible, stop the vehicle on a level surface,

away from traffic.

6. When the engine starts, let it idle for a few minutes.

2. Set the parking brake.

WARNING

3. See the engine manufacturer’s manual for instruc-

tions.

Do the next step exactly as instructed and do not

4. Call the Freightliner Customer Assistance Center at

allow the clamps of one cable to touch the clamps

1-800-385-4357 or 1-800-FTL-HELP.

of the other cable. Otherwise, a spark could occur

near a battery, possibly resulting in severe personal

injury from explosion and acid burns.

CAUTION

7. Disconnect the grounded cable from the frame or

Don’t crank the engine for more than 30 seconds at

other non-battery location; then disconnect the

a time during any of the following procedures. Wait

other end of the cable.

two minutes after each try to allow the starter to

8. Disconnect the remaining cable from the newly

cool. Failure to do so could cause starter damage.

charged battery first; then disconnect the other end.

5. Start the engine.

Running Out of Fuel

Changing a Flat Tire

IMPORTANT: If a flat tire occurs while driving,

WARNING

gradually decrease vehicle speed. Holding the

steering wheel firmly, move to a safe place on the

Do not mix gasoline or alcohol with diesel fuel. This

side of the road.

mixture could cause an explosion. When filling fuel

tanks, do not smoke or use an open flame near the

9.5

In an Emergency

1. If possible, stop the vehicle on a level surface,

Install the spare wheel and lug nuts. Make sure that

away from traffic.

the beveled sides of the nuts face inward, or, on

hub-piloted wheels, make sure that the hub-pilot

2. Apply the parking brake and place the transmission

pad is centered at the top.

in Park (P) or Neutral (N), for automatic transmis-

sions, or in First (1) gear for manual transmissions.

In a star pattern, tighten the nuts evenly until snug.

Turn the ignition switch to the OFF position.

10.

See Group 40 of the School Bus Chassis Work-

3. Turn on the emergency flashers.

shop Manual for wheel tightening patterns and

torque specifications. Lower the vehicle until the

4. Block the wheel diagonally opposite the wheel be-

wheel touches the ground. Tighten the nuts.

ing changed.

11.

Finish lowering the vehicle to the ground, then re-

5. Remove the spare wheel, jack, jack handle, and lug

move the jack.

wrench from storage.

12.

Remove the block, then stow the jack, jack handle,

NOTE: The jacking point for the front and rear

and lug wrench.

wheels is directly under the axle.

13.

After operating the vehicle for 50 to 100 miles (80

6. Place the jack on a solid surface. Insert the jack

to 160 km), retighten the wheel nuts to the speci-

handle and pump the handle slightly. Do not raise

fied torque values.

the wheel off of the ground yet. Loosen the wheel

lug nuts, but do not remove them.

IMPORTANT: The dual rear wheels are attached

using two-element lug nuts. The larger nut retains

the outer dual. The inner square stud retains the

inner dual. Remove and install these nuts sepa-

rately. The rear dual outer lug nut must be loos-

ened to check and retighten the inner nut.

7. Raise the vehicle until the wheel is off of the

ground. Remove the lug nuts and the wheel.

9.6

Specifications

Replacement Light Bulbs

Fluid and Lubricant Specifications

Recommended Fluid or

See Table 10.1 for a listing of replacement light bulbs.

Component

Lubricant

Front Axle Spindle Pins, Tie

Replacement Light Bulbs

Multipurpose Grease

Rods, Drag Link,

Lithium 12 Hydroxy

Light Location

Part Number

Intermediate Steering Shaft,

Stearate NLGI No. 2; for

Headlight, Rectangular, Halogen

WEE H6054

Front Brake and Clutch

temperatures below 0°F

Headlight, Rectangular, Standard

WEE 6052

Cable Pedal Shafts, Slip

(-18°C), use MIL-G-10924B

Spline and Universal Joints

Front Turn Signal Light

WEE 1156

Hydraulic Brake Master

Heavy-Duty DOT 3 Brake

Front Side Marker Light

WEE 193

Cylinder

Fluid

Instrument Panel Light

WEE 161

Brake and Clutch Pedal

Starplex 2 (lithium soap-

Rocker Switch Light

SPR 904 404

Pivots

based grease)

Table 10.1, Replacement Light Bulbs

Engine Oil

SAE 15W-40 HD

Transmission:

Fluids and Lubricants

SAE 40 or 50 above +10°F

Eaton/Fuller

(-12°C); SAE 30 below

See Table 10.2 for a listing of fluid and lubricant specifi-

+10°F (-12°C)

cations.

Allison *

Dexron III ATF

IMPORTANT: For vehicles with extended warran-

Grade No. 2-0 or 2-D

Fuel

Diesel Fuel

ties (and equipped with automatic transmissions),

use only TranSynd synthetic ATF.

Brake Caliper V-Ways and

Aeroshell Grade 5 (ES-

Anchor Plate Rails

1246)

Hypoid Gear Oil API

Rear Axle Differential

Service Classification GL-5

10.1

Specifications

Fluid and Lubricant Specifications

Recommended Fluid or

Component

Lubricant

50% Water/50% Ethylene

Engine Coolant

Glycol Antifreeze^†

A B

* For vehicles with extended warranties, use only TranSynd synthetic ATF.

†

See Group 20 of the School Bus Chassis Maintenance Manual for

Freightliner specifications.

Table 10.2, Fluid and Lubricant Specifications

Fuse/Relay/Circuit Breaker

Identification

NOTE: The fuse/relay/circuit breaker panel is lo-

06/13/96

f541287

cated on the right side of the dash. Depending on

Fig. 10.1, Fuse/Relay/Circuit Breaker Panel

vehicle options, fuse/relay/circuit breaker locations

may vary. See Fig. 10.1 or Table 10.3 for fuse/

Fuse/Relay/Circuit Breaker Identification

relay/circuit breaker locations and identification.

Pos.

Description

Part Number

Rating

No.

Ignition Bus/Standard

680 545 00 05

—

Circuits

Parking Brake Relay/

680 545 00 05

—

DRL

Ignition Bus/Optional

680 545 00 05

—

Circuits

AD Brake Light Relay

23-11276-011

—

10.2

Specifications

Fuse/Relay/Circuit Breaker Identification

Pos.

Description

Part Number

Rating

Description

Part Number

Rating

No.

231284 000010

10A Fuse

231284 000015

15A Fuse

Fuel Solenoid/Backup

Panel Lights

Lights

680 545 19 66

10A C.B.

680 545 20 66

15A C.B.

231284 000010

10A Fuse

LF 257 020

20A Fuse

Fan Clutch Relay

Fog Lights

680 545 19 66

10A C.B.

680 545 21 66

20A C.B.

231284 000010

10A Fuse

231284 000015

15A Fuse

Instrument Panel

Stoplight Switch

Feed

680 545 19 66

10A C.B.

680 545 16 66

15A C.B.

Hydraulic Brakes

231284 000005

5A Fuse

LF 257 020

20A Fuse

Daytime Running

231284 000010

10A Fuse

Lights, Battery Feed

680 545 17 66

20A C.B.

A10

Relay Coil Feeds

680 545 19 66

10A C.B.

231284 000015

15A Fuse

Horn

Ignition Controlled

680 545 01 34

20A Fuse

680 545 20 66

15A C.B.

A15

Relay, to Optional

680 545 12 66

20A C.B.

LF 257 020

20A Fuse

Ignition Bus

Turn Signal Flasher

Fog Light Relay

23-11276-011

—

680 545 21 66

20A C.B.

Taillight/Marker Lights

231284 000015

15A Fuse

23-11276-011

—

Ignition Switch,

Relay

Battery Feed

680 545 20 66

15A C.B.

Panel Light Relay

680 545 00 05

—

231284 000015

15A Fuse

Headlight Relay, Right

680 545 00 05

—

Headlight, Right

Headlight Relay, Left

680 545 00 05

—

680 545 16 66

15A C.B.

231284 000015

15A Fuse

231284 000015

15A Fuse

Taillights

B10

Headlight, Left

680 545 20 66

15A C.B.

680 545 16 66

15A C.B.

10.3

Specifications

Fuse/Relay/Circuit Breaker Identification

Pos.

Description

Part Number

Rating

Description

Part Number

Rating

No.

Ignition Controlled

680 545 01 34

20A Fuse

C17 ABS Relay

23-11276-011

—

B14

Relay, to Standard

C18 ABS Relay

23-11276-011

—

Ignition Bus

680 545 12 66

20A C.B.

C19 ABS Relay

23-11276-011

—

Hazard Warning

C20 ABS Relay

23-11276-011

—

Flasher:

Thermal

681 822 00 21

—

Table 10.3, Fuse/Relay/Circuit Breaker Identification

Solid State

680 822 00 21

—

231284 000010

10A Fuse

Accessory Feed

680 545 19 66

10A C.B.

231284 000010

10A Fuse

Ether Start

680 545 19 66

10A C.B.

LF 257 020

20A Fuse

Fuel/Water Separator,

Battery Power

680 545 21 66

20A C.B.

231284 000005

5A Fuse

Diagnostic Connector,

Battery Power

680 545 19 66

10A C.B.

231284 000005

Hydraulic ABS,

—

Battery Power

680 545 19 66

Fuel/Water Separator

C10

23-11276-011

—

Relay

Automatic

C15

Transmission

PAC14100455

—

Modulator

10.4

Index

Subject

Page

Subject

Page

Subject

Page

Starting the Vehicle in the

Turn Signal Lever

2.5

Correct Gear

4.1

Air Brake System

7.4

Vehicle Overload, or

Automatic Slack Adjusters

7.8

Overloading the Clutch

4.1

General Information

7.4

Cold Weather Operation

3.13

Driveline Parking Brake Burnishing . .

7.1

Meritor WABCO^® Antilock

Caterpillar

3.14

Braking System (ABS), Air

Cummins

3.15

Brake Systems

7.6

General Information

3.13

Operation

7.5

Emergency Starting With Jumper

Mercedes-Benz

3.15

Cables

9.3

Allison Automatic Transmissions

5.2

Cold Weather Starting

3.5

Engine Braking System (optional) . .

3.19

General Information

5.2

Caterpillar

3.5

Constant-Throttle Valves

Operation

5.3

Cummins

3.6

(MBE900 only)

3.19

Mercedes-Benz

3.6

Engine Break-In

3.7

Controls

2.1

Caterpillar

3.7

Changing a Flat Tire

9.5

Allison Automatic Transmission

Cummins

3.7

Clutch Adjustments

4.2

Controls

2.6

Mercedes-Benz

3.7

Clutch Lubrication

4.3

Cruise Control

2.7

Engine Operation

3.8

Clutch Operation

4.1

Electric Horn

2.8

Caterpillar

3.8

Coasting With the Clutch

Hazard Warning Light Tab

2.5

Cruise Control

3.12

Released (pedal depressed)

Headlight Dimmer Switch

2.5

Cummins

3.10

and the Transmission in Gear . .

4.2

Headlight Switch and Daytime

Mercedes-Benz

3.11

Engaging the Clutch While

Running Lights

2.1

Engine Shutdown

3.16

Coasting

4.2

Ignition Switch and Key

2.1

Caterpillar

3.16

Gear Shifting Techniques

4.1

Panel Light Control Lever

2.1

Cummins

3.17

Holding the Vehicle on an

Parking Brake Control Lever

2.3

Mercedes-Benz

3.18

Incline With a Slipping Clutch . .

4.2

Parking Brake Control Valve

2.4

Engine Starting

3.1

Reporting Erratic Clutch

Tilt/Telescope Steering Column

Operation Promptly

4.2

Caterpillar

3.2

(optional)

2.8

Riding the Clutch Pedal

4.2

Cummins

3.3

I-1

Index

Subject

Page

Subject

Page

Subject

Page

Mercedes-Benz

3.4

Hydraulic Brake System

7.1

Fuel Gauge

2.13

Pre-Start

3.1

General Information

7.1

Intake-Air Restriction Gauge . . .

2.14

Starting Precautions, All Engines

3.2

Meritor WABCO^® Antilock

Intake-Air Restriction Indicator . .

2.14

Braking System (ABS),

Exhaust Braking System (optional)

3.19

Speedometer

2.11

Hydraulic Brake Systems

7.2

General Information

3.19

Tachometer (optional)

2.10

Operation

7.2

Pacbrake^® Exhaust Brake

3.21

Transmission Oil Temperature

Gauge (optional)

2.13

Voltmeter (optional)

2.12

Instrument and Control Panel

2.1

Water Temperature Gauge

2.11

Federal Motor Vehicle Safety

Instrumentation Control Unit, Level

Standard (FMVSS) Labels

1.1

III

2.15

Fluids and Lubricants

10.1

Alert Screens

2.23

Fuller Straight-Shift Transmissions . .

5.1

Power Steering System

6.1

Brightness Control

2.17

General Information

5.1

Pretrip Inspection and Daily

Direct Access Screens

2.26

Operation

5.1

Maintenance Procedures

8.3

Fuel Use Efficiency Level

Fuse/Relay/Circuit Breaker

Pretrip Inspection Checklist

8.1

(FUEL)

2.16

Identification

10.2

Keypad

2.19

Level III ICU Ignition Sequence

2.19

Level III ICU Odometer

2.22

Replacement Light Bulbs

10.1

General Information

4.1

Level III ICU Roll Call

2.22

Running Out of Fuel

9.5

Stationary Access Screens—

Used With Parking Brake

Applied

2.26

Hazard Warning Lights

9.1

Starting After Extended Shutdown

Target MPG

2.16

Hood Tilting

2.32

or Oil Change

3.7

The Message Display Screen . .

2.21

To Return the Hood to the

Warning and Indicator Lights . . .

2.17

Operating Position:

2.32

Instruments

2.10

To Tilt the Hood:

2.32

Engine Oil Pressure Gauge

2.11

I-2