LEXUS SC400 1991 Service Repair Manual

Location of Connectors in Instrument Panel
BE±374±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName

±
BODY ELECTRICAL SYSTEM Door Lock Control SystemBE±375
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Check DOME fuse.NG OKCheck for short in all the harness
and components connected to the
DOME fuse (See attached wiring
diagram).1
Check and repair harness and connector
between ECU and battery. Proceed to next circuit inspection
shown on matrix chart (See page
BE±371
).
Repair or replace harness or
connector.
Check voltage between terminals +B1
and E of ECU connector.
Check for open in harness and connector
between ECU and body ground (See page
IN±27 ).
OK
OK
NG
NG
2
3
WIRING DIAGRAM
CIRCUIT INSPECTION
ECU Power Source Circuit
CIRCUIT DESCRIPTION
This circuit provides power to operate the theft deterrent and door lock ECU\
.
DIAGNOSTIC CHART
BE±376±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName

OKNG
NGOK
OKNG
INSPECTION PROCEDURE
1Check DOME fuse.
C
OK
PRemove DOME fuse from R/B No. 2.
Check continuity of DOME fuse.
Continuity
Check for short in all the harness and components con-
nected to the DOME fuse (See attached wiring diagram).
2Check voltage between terminals +B1 and E of ECU connector.
C
OK
P1. Remove the No. 1 under cover and heater duct.
2. Disconnect the theft deterrent and door lock ECUconnectors.
Measure voltage between terminals +B1 and E of ECU
connector.
Voltage: 10 ± 14 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±371).
3Check for open in harness and connector between ECU and body ground (Se\
e page IN±27).
Repair or replace harness or connector.
Check and repair harness and connector between
ECU and battery.
±
BODY ELECTRICAL SYSTEM Door Lock Control SystemBE±377
WhereEverybodyKnowsYourName

NGOK
NG
OK
1
2
Check P/W fuse.
Check voltage between terminal +B2 of
ECU connector and body ground.
Check and repair harness and connectors
between ECU and battery
(See page IN±27). Check for short in all the harness
and components connected to the
DOOR fuse (See attached wiring
diagram).
*1
Proceed to next circuit inspection
shown on matrix chart (See page
BE±371
).
WIRING DIAGRAM
*1: The power source is supplied to the actuator
(door lock motor, luggage compartment door
opener motor) through the theft deterrent and
door lock 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 (door lock motor circuit on
page BE±380 , and the luggage compartment
door opener motor circuit on page BE±382).
Actuator Power Source Circuit
CIRCUIT DESCRIPTION
This circuit provides power to drive the door lock motor and the luggage com\
partment door opener mo-
tor.
DIAGNOSTIC CHART
BE±378±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName

OKNG
NGOK
*1: The power source is supplied to the actuator (doorlock motor, luggage compartment door opener mo-
tor) through the theft deterrent and door lock ECU.
Accordingly, if a short circuit of the W/H or actuator
occurs in the actuator circuit, the DOOR fusible link
may become OPEN, so also inspect the actuator
(door lock motor circuit on page BE±380, and the
luggage compartment door opener motor circuit on
page BE±382 ).
INSPECTION PROCEDURE
1Check DOOR fuse.
C
OK
P1. Remove the No. 1 under cover and LH lower pad.
2. Remove the DOOR fusible link from J/B No. 1.
Check continuity of DOOR fuse.
Continuity
Check for short in all the harness and components con-
nected to the DPPR fusible link (See attached wiring dia-
gram). *1
2Check voltage between terminal +B2 of ECU connector and body ground.
C
OK
P1. Remove No. 1 under cover and heater duct.
2. Disconnect the theft deterrent and door lock ECU connector.
Measure voltage between terminal +B2 of ECU connec-
tor and body ground.
Voltage: 10 ± 14 V
Proceed to next circuit inpsection shown on matrix chart
(See page BE±371).
Check and repair harness and connectors be-
tween ECU and battery (See page IN±27).
±
BODY ELECTRICAL SYSTEM Door Lock Control SystemBE±379
WhereEverybodyKnowsYourName

NG
Check operating sound of door lock
motor.
OK NG OK
Check door lock motor.
Check and harness connectors between ECU
and door lock motor (See page IN±27). Replace door lock motor.
1
2
WIRING DIAGRAM
Proceed to next circuit inspection
shown on matrix chart (See page
BE±371
). Repair or replace door lock control
link.
Repair or replace harness or
connector.
3
OK
NG
Door Lock Motor Circuit
CIRCUIT DESCRIPTION
The door lock motor locks and unlocks the door in accordance with signals f\
rom the ECU.
DIAGNOSTIC CHART
HINT: Inspect the door which is malfunctioning.
BE±380
±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName

NGOK
NGOK
OKNG
INSPECTION PROCEDURE
1Check operating sound of door lock motor.
C
OK
Hint
Check operating sound of door lock motor, when door
lock control switch is pushed to the lock side and unlock
side.
Can hear operating sound of door lock motor.
Inspect the door which is malfunctioning.
Repair or replace door lock control link.
2Check door lock motor.
C
OK
Hint
P1. Remove the door trim and service hole cover.
2. Disconnect the door lock motor connector.
1. Connect positive lead to terminal 5 and nega-
tive  lead to terminal 2 o door lock motor connec-
tor.
2. Connect positive  lead to terminal 2 and negative
 lead to terminal 5 of, door lock motor connector.
1. Door lock motor locks door.
2. Door lock motor unlocks door.
Perform inspection in a short time (within 2 seconds).
Replace door lock motor.
3Check harness and connectors between ECU and door lock motor (See page \
IN±27).
Repair or replace harness or connector.
Proceed to next circuit inspection shown on ma-
trix chart (See page BE±371).
±
BODY ELECTRICAL SYSTEM Door Lock Control SystemBE±381
WhereEverybodyKnowsYourName

NG
Check voltage between terminal 1 of lug-
gage compartment door opener motor and
body ground.
OK NG
OK
Check luggage compartment door opener
motor.
Proceed to next circuit inspection
shown on matrix chart (See page
BE±371 ). Check harness and connectors
between ECU and luggage
compartment door opener motor
(See page
IN±27).
Replace luggage compartment
door motor.
1
2
WIRING DIAGRAM
Luggage Compartment Door Opener Motor Circuit
CIRCUIT DESCRIPTION
This circuit unlocks the luggage compartment door when the ECU sends signals\
to the luggage
compartment door opener motor.
DIAGNOSTIC CHART
BE±382±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName

OKNG
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal 1 of luggage compartment door opener motor and body
ground.
C
OK
P1. Remove luggage compartment trim rear cover.
2. Disconnect the opener motor connector.
Measure voltage between terminal 1 of luggage
compartment door opener motor and body ground,
when opener switch is pulled and not pulled.
Check harness and connectors between ECU and lug-
gage compartmtne door opener motor (See page IN±27).
2Check luggage compartment door opener motor.
C
OK
Hint
Connect positive  lead to the opener motor connector
and negative lead to the body of the opener motor.
Operated motor shaft and gear.
Perform inspection in a short time (within 1 second).
Replace luggage compartment door opener motor.
Proceed to next circuit inpsection shown on ma-
trix chart (Seepage BE±371).
±
BODY ELECTRICAL SYSTEM Door Lock Control SystemBE±383
WhereEverybodyKnowsYourName