Lotus Elise / Lotus Exige. Instruction - part 105

 

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Lotus Elise / Lotus Exige. Instruction - part 105

 

 

    

Lotus Service Notes                               Section WD

Page 3

WD.1 - GENERAL DESCRIPTION

The Lotus Elise for USA markets, introduced for 2005 model year, is equipped with a driver and passen-

ger frontal airbag system, which includes pyrotechnic seat belt pre-tensioners for both the driver and passen-
ger.  The airbag Supplementary Restraint System (SRS) is supplemental to the seat belts, and does not render
the seat belts redundant.  Seat belts have proven to be the single most effective safety device, and should be
worn at all times by both driver and passenger, no matter how short the journey.  Properly worn seat belts also
ensure that the seat occupant is in the best position for full effectiveness of the airbag.

WARNING:  Airbags inflate with great force, in a fraction of a second, and if a vehicle occupant is too
close to the airbag (less than 10 inches {250 mm}) or incorrectly positioned, they could be killed or
seriously injured.

The SRS is designed to operate when the vehicle is involved in a frontal, or near frontal collision, and the

impact (rate of deceleration) as detected by a vehicle mounted sensor, is sufficient to warrant airbag and seat
belt tensioning protection to both occupants.  The airbag for the driver is housed in the centre of the steering
wheel, and that for the passenger in the front of the fascia.  When triggered, both bags inflate in a fraction of a
second to form a cushion for the driver's and passenger's upper bodies.  The bags then deflate very rapidly to
minimise any obstruction to the driver.  Initiated at the same time as the airbags is a pyrotechnic device on
each seat belt reel assembly, which uses a rack and pinion mechanism in order to apply a tightening force to
the belt reel and remove any slack from the belt.  The force sustained by the belt and its user is then controlled
by a torsion bar within the belt reel to limit the deceleration force to which the occupant is subjected.

Note that the SRS will deploy only in moderate to severe frontal and near frontal collisions, and is not

designed to be triggered in rollover, rear or low speed frontal collisions, or in some types of side impacts.

The system incorporates a self-diagnostic facility, which continuously monitors the SRS electrical circuits

for faults, and if necessary, lights a tell tale lamp in the instrument cluster.  Most components of the SRS will
require replacement after an airbag deployment.

WD.2 - AIRBAG TELL TALE

A tell tale lamp in the instrument cluster will light for a few seconds following ignition switch on, and then

go out.  If the lamp remains lit, or comes on at any other time, a fault in the airbag system is indicated.

WARNING:  If the airbag tell tale does not operate as described above, a fault in the SRS system is
indicated.  The airbags may not inflate correctly or at all, or may inflate without warning.  The system
should be interrogated using the Lotus Scan tool, and diagnosed and rectified without delay.

WD.3 - DATA LINK CONNECTOR (DLC)

In order to provide for communication

with the SRS Sensing and Diagnostic Module
(SDM), the Lotus Scan tool may be plugged
into the special 16 terminal harness connec-
tor socket, known as a Data Link Connector,
located off the main harness and accessible
from the passenger footwell.  Communication
with engine management and anti-lock brakes
is also available via this connector.

Main harness

      em235a

Data Link Connector (DLC)

    

Lotus Service Notes                               Section WD

Page 4

WD.4 - TROUBLE CODES

All the time the ignition is switched on, the Sensing and Diagnostic Module (SDM) continuously monitors

the resistance of various parts of the SRS electrical circuit, and compares these values with pre-programmed
tolerance bands to enable it to recognise 'faults' in the system and light the airbag tell tale lamp in the instru-
ment cluster.  If such a fault is detected, the SDM stores a 'Trouble Code' for that particular type of fault in its
memory.
i).

Current (Present) Codes - Faults that are currently being detected.  Current codes are stored in the SDM
Random Access Memory (RAM), which will be cleared if the vehicle battery is disconnected.

ii).

History (Not present) Codes - All faults detected since the last time faults were cleared from the memory
using the Lotus Scan tool.  History codes are stored in the SDM Electronically Erasable Programmable
Read Only Memory (EEPROM) and are not cleared if the battery is disconnected.

Vehicle crash data is also stored in coded form in the SDM and is not erasable.  New SDMs are supplied

only against V.I.N. and on exchange with the old unit.

WD.5 - LOTUS SCAN TOOL

In order to provide for communication with the airbag SDM, engine management system ECU and anti-

lock brake system, a hand held electronic scanner 'Lotus Scan 2' (part number T000T1418F), may be plugged
into the Data Link Connector (see earlier)

Amongst the operations available using the 'Lotus Scan 2' tool are:

-

Reading of Trouble Codes

-

Clearing of Trouble Codes

-

Reading live data

Operating instructions are provided with the tool.

Important Note

The power supply transformer is used for overnight charging of the printer, and also for powering  the

Scan 2 tool during software downloading from a PC (personal computer).  For the software download opera-
tion, the Scan tool requires a power supply from the mains via the transformer and an inverter.  Two types of
inverter have been used; early kits used an adaptor lead to plug into the bottom end of the Scanner tool.  Later
kits use an adaptor plug fitting into the top end of the scanner.

When charging the printer, it is most important that the inverter is NOT used, or damage to the

transformer may be caused.  Incorrect connection is possible only with the early type adaptor lead, with which
extra care should be exercised.

1.

Reading data from vehicle

Data Link Connector (DLC)

Scan 2

(front of passenger footwell)

Printer

  em192a

    

Lotus Service Notes                               Section WD

Page 5

2.

Downloading software from P.C.

With early type adaptor lead

Connect to COM

Power

port on PC

supply
transformer

Adaptor lead used
to connect to
transformer

  em192c

3.

Charging printer

Power supply
transformer

Do NOT use adaptor
lead for this application

Printer

With later type adaptor

Connect to COM
port on PC

Power
supply
transformer

Power supply adaptor

    em192f

    

Lotus Service Notes                               Section WD

Page 6

WD.6 - SAFETY PRECAUTIONS, SHIPPING, STORAGE & DISPOSAL

WARNING:  The SDM can maintain sufficient voltage to cause an airbag deployment for up to 20
seconds after the battery has been disconnected.  Before working on the airbag system, or in close
proximity to an airbag, first take the following precautions to temporarily disable the airbag system:

1.

Turn off the ignition.

2.

Before disconnecting the battery, use the Lotus Scan tool to read any stored trouble codes.

3.

Disconnect the negative (earth) lead from the battery and tape back to ensure that no contact with the
battery negative terminal can be made.

4.

Wait for 30 seconds.

5.

If working on or near the steering wheel, locate the yellow harness connector alongside the steering
column near the column upper fixing.  Unplug this connector.  Note that the connector is fitted with
'shorting bars' which automatically interconnect the high and low terminals of the airbag to prevent acci-
dental deployment caused by a voltage differential.

When service work has been completed, reconnect the harness plug and secure with its locking feature,

and reconnect the battery.  Ensure the airbag tell tale lights for a few seconds with ignition and then goes out.

Storage
-

Airbag modules and SDMs should not be stored at temperatures above 176°F (80°C).

-

Airbag modules and SDMs should not be stored in damp conditions.

-

Do not store airbag module or SDM boxes more than two high.

-

Always store and handle airbag modules and SDMs in an upright position.  Never store SDMs upside

down.

Sensor & Diagnostic Module (SDM)

The SDM is calibrated specifically to the Elise, and is mounted on a dedicated bracket to the scuttle

beam.  Never use an SDM from another vehicle, or modify its mounting to the Elise.

WARNING:

Handle the SDM with great care.  Never strike or jar the SDM as this could cause airbag deploy-
ment and result in personal injury or improper operation of the SRS.

All module and mounting bracket bolts must be correctly installed and tightened to assure proper
security and operation.

Never power up the SRS when the SDM is not properly mounted and secured, since the SDM is
easily triggered when not attached, and could result in deployment causing personal injury.

Do not use or attempt to repair a damaged SDM.

Inflator Module
Live (Undeployed) Inflator Modules:  Special care is necessary when handling and storing a live (undeployed)
inflator module.  In the unlikely event of accidental deployment, the rapid gas generation produced during
deployment of the air bag could cause violent movement of the inflator module or surrounding objects, and
result in personal injury.

WARNING:

When carrying a live inflator module, make sure the bag and trim cover are pointed away from
you.  In case of an accidental deployment, the bag will then deploy with minimal chance of injury.

When placing a live inflator module on a bench or other surface, always face the bag and trim
cover upwards, away from the surface.  This is necessary so that a free space is provided to allow
the air bag to expand in the unlikely event of accidental deployment.  Otherwise, personal injury
may result.

Never carry the inflator module by the wires or connector on the underside of the module.

Do not use or attempt to repair a damaged inflator module, and NEVER apply any electrical power
to the module except as specified in the diagnostic procedures.

Inflator Module Shipping Procedures for Live (Undeployed) Inflator Modules

The transportation of uninstalled inflator modules is regulated by the Hazardous Materials Regulations of

 

 

 

 

 

 

 

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