Lexus ES300 (1997 year). Manual - part 402

–

DIAGNOSTICS

POWER SEAT CONTROL SYSTEM

DI–385

537

1997 LEXUS ES300   (RM511U)

2

Check harness and connectors between Seat Position Control ECU and position
sensors (See page 

IN–27

).

NG

Repair or replace harness or connectors.

OK

Check and replace Seat Position Control
ECU.

N21263

Instrument Panel J/B

Instrument Panel J/B

Stop Light Switch

Seat Position Control ECU

22

S15

STOP

Stop Light

Light Failure Sensor

STOP

1C

G–W

7

1R

G–W

G–W

G–W

W

1

1

2

1R

BS2

G–W

4

2

DI–386

–

DIAGNOSTICS

POWER SEAT CONTROL SYSTEM

538

1997 LEXUS ES300   (RM511U)

Stop Light Switch Circuit

CIRCUIT DESCRIPTION

The stop light switch sends a brake ON or OFF signal to the ECU. When the ECU receives a brake ON signal,
it prohibits return operation of the seat.

WIRING DIAGRAM

INSPECTION PROCEDURE

1

Check stop light operation.

CHECK:
Check that the stop light comes on when the brake pedal is depressed, and turns off when the pedal is re-
leased.

NG

Check stop light circuit (See page 

BE–2

).

OK

DI0GB–01

N21255

Seat Position Control ECU

Connect

(–)

(+)

STOP

22

–

DIAGNOSTICS

POWER SEAT CONTROL SYSTEM

DI–387

539

1997 LEXUS ES300   (RM511U)

2

Check voltage between terminal STOP of Seat Position Control ECU connector
and body ground.

PREPARATION:
Remove Seat Position Control ECU with connectors still con-
nected.
CHECK:
Measure voltage between terminal STOP of Seat Position Con-
trol ECU and body ground when the brake pedal is depressed
and released.
OK:

Brake pedal

Voltage

Depressed

10 

∼

 14 V

Released

0 V

OK

Proceed to next circuit inspection shown on
matrix chart (See page 

DI–374

).

NG

Check and repair harness and connector be-
tween Seat Position Control ECU and stop
light switch.

N21264

Instrument Panel J/B

Seat Position Control ECU

G–W

J/C

21

B

Park/Neutral
Position Switch

GAUGE

R–L

J28

IK2

4

1J

10

G–W

G–W

J29

R–L

R–L

IK2

J/C

B

D

F

2

A

A

R–L

7

2

P

S15

BS2

G–W

DI–388

–

DIAGNOSTICS

POWER SEAT CONTROL SYSTEM

540

1997 LEXUS ES300   (RM511U)

Park/Neutral Position Switch Circuit

CIRCUIT DESCRIPTION

The park/neutral position switch detects the P position when the lever is shifted into P and sends a signal
to the ECU. When the return switch is turned ON with the IG SW ON and the shift in P position, the ECU
performs return operation.

WIRING DIAGRAM

INSPECTION PROCEDURE

1

Check shift position indicator.

CHECK:
Check that P lights up on the shift indicator when P position is shifted into, and that P is OFF when shifting
into another position.

NG

Check shift position indicator circuit 
(See page 

BE–2

).

NG

DI0GE–01