Lexus ES300 (1997 year). Manual - part 400

N21260

Seat Position Control ECU

SGND

SYSB

Battery

ECU–B

R/B No.2

BR

2J

1V

B

J/C

BR

W–R

W–R

W–R

2A

1W

B

9

1

9

4

5

1

7

BS2

Instrument Panel J/B

W–R

ID1

SHOR

T–PIN

B–G

FL MAIN

BS2

10

3

IH

S15

S15

W–R

N21252

SGND

SYSB

LOCK

11

9

(+)

(–)

Connect

Seat Position Control ECU

–

DIAGNOSTICS

POWER SEAT CONTROL SYSTEM

DI–377

529

1997 LEXUS ES300   (RM511U)

ECU Power Source Circuit

CIRCUIT DESCRIPTION

This circuit provides power for ECU operation and is also the power source for the sensor.

WIRING DIAGRAM

INSPECTION PROCEDURE

1

Check voltage between terminals SYSB and SGND of Seat Position Control ECU
connector.

PREPARATION:
Remove Seat Position Control ECU with connectors still con-
nected.
CHECK:
Measure voltage between terminals SYSB and SGND of Seat
Position Control ECU connector.
OK:
Voltage: 10 – 14 V

OK

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

DI–374

).

NG

DI0G1–01

N21253

Seat Position Control ECU

Disconnect

(+)

(–)

11

SGND

DI–378

–

DIAGNOSTICS

POWER SEAT CONTROL SYSTEM

530

1997 LEXUS ES300   (RM511U)

2

Check continuity between terminals SGND of Seat Position Control ECU connec-
tor and body ground.

CHECK:
Measure resistance between terminal SGND of Seat Position
Control ECU connector and body ground.
OK:
Resistance: Continuity (below 1 

Ω

)

NG

Repair or replace harness or connector.

OK

3

Check ECU–B fuse.

NG

Check for short in all the harness and compo-
nents connected to ECU–B fuse and repair them
(See attached wiring diagram).

OK

Check and repair harness or connector be-
tween Seat Position Control ECU and battery.

N21261

Reclining Motor

Slide Motor

Rear Vertical Motor

Front Vertical Motor

Seat Position Control ECU

RCL–

RCL+

SLD–

SLD+

RRV–

RRV+

FRV–

FRV+

R–B

R–G

L–B

L

L–Y

R

L–R

R–L

GND

8

A

2

J/C

5

W–B

W–B

4

3

2

1

6

9

10

7

1

2

1

2

2

1

1

S14

BN

BS2

S14

S14

S14

S14

S14

S14

S14

S14

N21468

2

Slide Motor

2

1

1

–

DIAGNOSTICS

POWER SEAT CONTROL SYSTEM

DI–379

531

1997 LEXUS ES300   (RM511U)

Motor Circuit

CIRCUIT DESCRIPTION

The Seat Position Control ECU controls the 4 motors for slide, front vertical, rear vertical and reclining.

WIRING DIAGRAM

INSPECTION PROCEDURE

1

Check motor.

PREPARATION:
1. Remove seat.
2. Disconnect each motor connector.
CHECK:
Check seat movement when battery positive voltage is applied
to each motor.
Slide motor
CHECK:
Connect battery 

 to terminal 2 and battery 



 to terminal 1 of

the slide motor connector.
OK:
The seat moves forward.
CHECK:
Connect battery 



 to terminal 2 and battery 

 to terminal 1 of

the slide motor connector.
OK:
The seat moves back.

DI0G4–01

N21467
N21465
N21466

I00528

Front Vertical Motor

Reclining Motor

Rear Vertical Motor

2

1

2

1

2

1

2

1

2

1

2

1

DI–380

–

DIAGNOSTICS

POWER SEAT CONTROL SYSTEM

532

1997 LEXUS ES300   (RM511U)

Front vertical motor
CHECK:
Connect battery 

 to terminal 2 and battery 



 to terminal 1 of

the front vertical motor connector.
OK:
The front of the seat cushion rises.
CHECK:
Connect battery 



 to terminal 2 and battery 

 to terminal 1 of

the front vertical motor connector.
OK:
The front of the seat cushion lowers.

Rear vertical motor
CHECK:
Connect battery 

 to terminal 2 and battery 



 to terminal 1 of

the rear vertical motor connector.
OK:
The front of the seat cushion rises.
CHECK:
Connect battery 



 to terminal 2 and battery 

 to terminal 1 of

the rear vertical motor connector.
OK:
The front of the seat cushion lowers.

Reclining motor
CHECK:
Connect battery 

 to terminal 2 and battery 



 to terminal 1 of

the reclining motor connector.
OK:
The seat back return to up right.
CHECK:
Connect battery 



 to terminal 2 and battery 

 to terminal 1 of

the reclining motor connector.
OK:
The seat back reclining.

NG

Replace motor.

OK