Lexus ES300 (1997 year). Service manual - part 428

AB0119
N19821

I00737

ON

1

2

–

DIAGNOSTICS

CRUISE CONTROL SYSTEM

DI–489

641

1997 LEXUS ES300   (RM511U)

INSPECTION PROCEDURE

1

Check resistance between terminals MO and MC of actuator motor.

PREPARATION:
(a)

Turn ignition switch OFF.

(b)

Disconnect the actuator connector.

CHECK:
Measure resistance between terminals 1 and 2.
HINT:
If control plate position is fully opened or fully closed, resistance
can not measure.
OK:

Resistance: more than 4.2 

Ω

NG

Replace cruise control actuator.

OK

2

Check for open and short in harness and connectors between cruise control
ECU and actuator motor (See page 

IN–27

).

NG

Repair or replace harness or connector.

OK

Check and replace cruise control ECU.
(See page 

IN–27

).

N21217

Cruise Control ECU

2

1

3

4

3

to STOP Fuse

8

Stop Light Switch

4

Cruise Control Actuator

 Actuator Magnetic Clutch

J8

J8

A

A

Junction
Connector

1J

1J

A

Junction
Connector

Instrument
Panel J/B

Instrument
Panel J/B

1R

1R

A

A

Junction
Connector

2

L

STP–

J15

J3

J10

J27

C14

C14

G–W

G–W

G–W

W–B

R–Y

G–B

W–B

W–B

W

4

5

7

8

II

DI–490

–

DIAGNOSTICS

CRUISE CONTROL SYSTEM

642

1997 LEXUS ES300   (RM511U)

DTC

    12

Actuator Magnetic Clutch Circuit

CIRCUIT DESCRIPTION

This circuit turns on the magnetic clutch inside the actuator during cruise control operation according to the
signal from the ECU. If a malfunction occurs in the actuator or speed sensor, etc. during cruise control opera-
tion, the rotor shaft between the motor and control plate is released.
When the brake pedal is depressed, the stop light switch turns on, supplying electrical power to the stop light.
Power supply to the magnetic clutch is mechanically cut and the magnetic clutch is turned OFF.
When driving downhill, if the vehicle speed exceeds the set speed by 15 km/h (9 mph), the ECU turns the
safety magnet clutch OFF. If the vehicle speed later drops to within 10 km/h (6 mph) above the set speed,
then cruise control at the set speed is resumed.

DTC No.

Detection Item

Trouble Area

12



Short in actuator magnetic clutch circuit.



Open (0.8 sec.) in actuator magnetic clutch circuit.



STOP Fuse



Stop light switch



Actuator magnetic clutch



Harness or connector between cruise control ECU and

actuator magnetic clutch, actuator magnetic clutch and body

ground



Cruise control ECU

WIRING DIAGRAM

DI0EP–01

N20675

Instrument Panel Junction Block No.1

STOP Fuse

N09044

2

1

4

3

–

DIAGNOSTICS

CRUISE CONTROL SYSTEM

DI–491

643

1997 LEXUS ES300   (RM511U)

INSPECTION PROCEDURE

1

Check STOP fuse.

PREPARATION:
(a)

Turn ignition switch OFF.

(b)

Remove the STOP fuse from instrument panel junction
block No.1.

CHECK:
Check fuse continuity.
OK:

There is continuity.

NG

Replace STOP fuse.

OK

2

Check stop light switch.

PREPARATION:
Disconnect the stop light switch connector.
CHECK:
Check continuity between terminals.

Switch position

Continuity

Switch pin free

(Brake pedal depressed)

1 – 2

Switch pin pushed in

(Brake pedal released)

3 – 4

NG

Replace stop light switch.

OK

N21919

4

3

DI–492

–

DIAGNOSTICS

CRUISE CONTROL SYSTEM

644

1997 LEXUS ES300   (RM511U)

3

Check resistance between terminals L and GND of actuator magnetic clutch.

PREPARATION:
(a)

Turn ignition switch OFF.

(b)

Disconnect the actuator connector.

CHECK:
Measure resistance between terminals 3 and 4.
OK:

Resistance: 34.65 

 42.35 

Ω

.

NG

Replace cruise control actuator.

OK

4

Check for open and short in harness and connectors between cruise control
ECU and actuator magnetic clutch, actuator magnetic clutch and body ground
(See page 

IN–27

).

NG

Repair or replace harness or connector.

OK

Check and replace cruise control ECU 
(See page 

IN–27

).