Lexus SC300 / Lexus SC400. Manual - part 180

NG

OK

OK

NG

3

Check voltage between terminals B1 and E1 of power seat switch connector.

C

OK

P

Remove power seat switch with connector still con-
nected.

Measure voltage between terminal B1 and E1 of power
seat switch connector.

Voltage:

10 – 14 V

Go to step 5.

4

Check continuity between terminal E1 or power seat switch connector and body ground.

C

OK

P

Disconnect power seat switch connector.

Check continuity of E1 terminal.

Resistance:

1 

 or less

Repair or replace harness or connector.

Check for open and short in harness and connec-

tor between ECU and battery (See page 

IN–27

).

BE–336

–

BODY ELECTRICAL SYSTEM

Power Seat Control System (Passenger’s Seat)

OK

NG

OK

NG

5

Check power seat switch.

C

OK

P

Disconnect power seat switch connector.

Check continuity of each terminal.

Continuity

Terminal

Switch Position

Side

Neutral

Forward

Back

1

3

4

2

Replace power seat switch.

6

Check for open and short in harness and connectors between ECU and power seat switch.  (See

page 

IN–27

).

Repair or replace harness or connector.

Check and replace ECU.

–

BODY ELECTRICAL SYSTEM

Power Seat Control System (Passenger’s Seat)

BE–337

WIRING DIAGRAM

Buckle Switch Circuit

CIRCUIT DESCRIPTION

Buckle switch signal is sent to ECU when the passenger’s seat belt is fastened.
When the signal is input to ECU, ECU prohibits operation of the power walk–in.

DIAGNOSTIC CHART

DIAGNOSTIC CHART

Check buckle switch.

Check voltage between terminals PBCL
and SGND of ECU connector.

OK

NG

OK

OK

NG

NG

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

BE–319

).

Replace the buckle switch.

Check the harness and connector between
buckle switch and ECU, ECU and battery.

Repair or replace harness or
connector.

Check and replace ECU.

BE–338

–

BODY ELECTRICAL SYSTEM

Power Seat Control System (Passenger’s Seat)

NG

OK

OK

NG

OK

NG

INSPECTION PROCEDURE

1

Check voltage between terminal PBCL and SGND of ECU connector.

C

OK

P

Remote ECU with connectors still connected.

Measure voltage between terminals PBCL and SGND
of ECU connector, when buckle switch is on and off.

With switch ON (Tung plate
is inserted into buckle
switch)

With switch OFF (Tung plate is
inserted into buckle switch)

Below 1 V

10 – 14 V

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

BE–319

).

2

Check buckle switch.

C

OK

P

Disconnect buckle switch connector.

Check continuity between terminal 1 and 2 of buckle
switch connector.

Terminal

Switch
condition

ON

OFF

Continuity

1

2

Replace buckle switch.

3

Check for open and short in harness and connector between buckle switch and ECU, ECU and

battery (See page 

IN–27

).

Repair or replace harness or connector.

Check and replace ECU.

–

BODY ELECTRICAL SYSTEM

Power Seat Control System (Passenger’s Seat)

BE–339