LEXUS SC400 1991 Service Repair Manual

LOCATION OF CONNECTORS
Location of Connectors in Engine Compartment
BE±320±
BODY ELECTRICAL SYSTEM Power Seat Control System (Passenger's Seat)
WhereEverybodyKnowsYourName

Location of Connectors in Instrument Panel
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Passenger's Seat)BE±321
WhereEverybodyKnowsYourName

Location of Connectors in Body
BE±322±
BODY ELECTRICAL SYSTEM Power Seat Control System (Passenger's Seat)
WhereEverybodyKnowsYourName

Location of Connectors in Seat
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Passenger's Seat)BE±323
WhereEverybodyKnowsYourName

WIRING DIAGRAM
CIRCUIT INSPECTION
ECU Power Source Circuit
CIRCUIT DESCRIPTION
This circuit provides power for ECU operation and is also the power source f\
or the slide position sensor.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
Check DOME fuse.NG
OK
NG NG
OK
OK Check for short in all the harness
and components connected to
DOME fuse. (See attached wir-
ing diagram).
Check voltage between terminals SYSB and
GND of ECU connector. Proceed to next circuit inspection
shown on matrix chart.
(See page
BE±319).
Check continuity between terminal GND of
ECU connector and body ground. Repair or replace harness or
connector.
Check and repair harness or connector
between ECU and battery.
BE±324±
BODY ELECTRICAL SYSTEM Power Seat Control System (Passenger's Seat)
WhereEverybodyKnowsYourName

OKNG
NGOK
OKNG
INSPECTION PROCEDURE
1Check DOME fuse.
Check for short in all the harness and components con-
nected to DOME fuse and repair them (See attached wir-
ing diagram).
2Check voltage between terminals SYSB and GND of ECU connector.
C
OK
PRemove ECU with connectors still connected.
Measure voltage between terminals SYSB and GND of
ECU connector.
Voltage: 10 ±14 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±319).
3Check continuity between terminal GND of ECU connector and body ground.
C
OK
Measure resistance between terminal GND of ECU con-
nector and body ground.
Resistance: 1
or less
Repair or replace harness or connector.
Check and repair harness or connector between
ECU and battery.
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Passenger's Seat)BE±325
WhereEverybodyKnowsYourName

Check DOOR fuse.NG
OK
NG
OK NGOK Check for short in all the harness
and components connected to
the DOOR fuse (See attached
wiring diagram). *
1
Check voltage between terminals +B and
GND of ECU connector.
Proceed to next circuit inspection
shown on matrix chart (See page
BE±319
).
Check continuity between terminal GND of
ECU connector and body ground. Repair or replace harness of
connector.
Check and repair harness or connector
between ECU and battery. *
1The power source is supplied to the actuator
(Slide motor) through the passenger's seat
ECU accordingly, if a short circuit of the W/H
or actuator occurs in the actuator circuit, the
DOOR fuse may become open, so also in-
spect the actuator. (Slide motor circuit on
page
BE±328 ).
WIRING DIAGRAM
Slide Motor Power Source Circuit
CIRCUIT DESCRIPTION
This is the power source for slide motor.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BE±326±
BODY ELECTRICAL SYSTEM Power Seat Control System (Passenger's Seat)
WhereEverybodyKnowsYourName

OKNG
NGOK
OKNG
INSPECTION PROCEDURE
1Check DOOR fuse.
Check for short in all the harness components con-
nected to the DOOR fuse and repair them (See attached
wiring diagram). *1
2Check voltage between terminals +B and GND of ECU connector.
C
OK
PRemove passenger's seat ECU with connectors still
connected.
Measure voltage between terminals +B and GND of
ECU connector.
Voltage: 10 ± 14 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±319).
3Check continuity between terminal GND of ECU connector and body ground.
C
OK
Measure resistance between terminal GND of ECU and
body ground.
Resistance: 1
or less
Repair or replace harness or connector.
Check and repair harness or connector between
ECU and battery.
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Passenger's Seat)BE±327
WhereEverybodyKnowsYourName

WIRING DIAGRAM
Slide Motor Circuit
CIRCUIT DESCRIPTION
The passenger's seat ECU control the slide motor.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
Check slide motor.NG
NG
OK
OK Replace motor.
Repair or replace harness or
connector.
Check harness and connector between
ECU and motor (See page
IN±27).
Proceed to next circuit inspection shown
on matrix chart (See page BE±319).
BE±328±
BODY ELECTRICAL SYSTEM Power Seat Control System (Passenger's Seat)
WhereEverybodyKnowsYourName

OKNG
OKNG
INSPECTION PROCEDURE
1Check Slide Motor.
C
OK
P(1) Remove Seat
(2) Disconnect slide motor connector.
Check seat movement when battery voltage is applied
to slide motor.
Connect positive
(negative  ) terminal to terminal 1
of slide motor connector and negative  (positive
)
terminal to terminal 2.
Terminal
Movement
Forward
Back
12
Replace motor.
2Check for open and short in harness and connector between ECU and motor (See\
page IN±27).
Repair or replace harness or connector.
Proceed to next circuit inspection shown on ma-
trix chart (See page BE±319).
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Passenger's Seat)BE±329
WhereEverybodyKnowsYourName