ECU LEXUS SC400 1991 Service Repair Manual

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
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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
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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
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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
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Door Lock Control Switch Circuit
CIRCUIT DESCRIPTION
When the door lock control switch is pushed to the lock side, Lock terminal of the swi\
tch is grounded,
and when the switch is pushed to the unlock side, Unlock terminal is grounded (See wiring diagram
below).
WIRING DIAGRAM
NG
Check voltage between terminals 2 (3), 1(1)
of door lock control switch connector and
body ground.
OK NG OK
Check door lock control switch.
Check harness and connectors between ECU
and door lock control switch, switch and body
ground (See page IN±27). Replace door lock control switch.
1
2
Proceed to next circuit inspection
shown on matrix chart (See page
BE±371
).
Check and replace ECU Repair or replace harness or
connector.
3
OK
NG
DIAGNOSTIC CHART
BE±384±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName

NGOK
OKNG
OKNG
*1: malfunction of the ECU can be considered possibleonly when the problem symptom is the following:

Lock and/or unlock using the Door Lock Con-
trol Switch cannot be done, neither on the driv-
er's side nor on the passenger's side.
INSPECTION PROCEDURE
1Check voltage between terminals 2(3), 1(1) of door lock control switch co\
nnector and body
ground.
C
OK
Hint
PRemove the door trim and service hole cover.
1. Turn ignition switch ON.
2. Measure voltage between terminals 2(3), 1(1) of door lock control switch connector and body
ground, when door lock control switch is pressed to
the lock side, unlock side and not pressed.
The terminal number without brackets is for the LH, the
number with brackets is for the RH.
Proceed to next circuit inspection shown on matrix chart
(See page BE±371).
2Check door lock control switch.
C
OK
Hint
PDisconnect the door lock control switch connector.
Check continuity between terminals 2(3), 1(1), and 8(2)
of door lock control switch connector, when door lock
control switch is pressed to the lock side, and unlock
side and not pressed.
The terminal number without brackets is for the LH, the
number with brackets is for the RH.
Replace door lock control switch.
3Check harness and connectors between ECU and door lock control switch, s\
witch and body
ground (See page IN±27).
Repair or replace harness or connector.
Check and replace ECU. *1
±
BODY ELECTRICAL SYSTEM Door Lock Control SystemBE±385
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Door Key Lock and Unlock Switch Circuit
CIRCUIT DESCRIPTION
The door key lock and unlock switch is built in the door key cylinder.
When the key is turned to the lock side, terminal 3 of the switch is grounde\
d and when the key is turned
to the unlock side, terminal 1 of the switch is grounded.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
OKOK NG NG
Check door key lock and unlock switch.
Check harness and connectors between ECU
and switch, switch and body ground
(See page IN±27). Replace door key lock and unlock
switch.
1
2
Proceed to next circuit inspection shown on
matrix chart (See page
BE±371). Repair or replace harness or
connector.
WIRING DIAGRAM
BE±386±
BODY ELECTRICAL SYSTEM Door Lock Control System
WhereEverybodyKnowsYourName

OKNG
OKNG
INSPECTION PROCEDURE
1Check door key lock and unlock switch.
C
OK
P1. Remove the door trim and service hole cover.
2. Disconnect the door ley lock and unlock switch con-
nector.
Check continuity between terminals 1, 2 and 3 of door
key lock and unlock switch is turned to the lock side, un-
lock side and not turned.
Replace door key lock and unlock switch.
2Check harness and connectors between ECU ans switch, switch and body ground (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±387
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OKOK NG NG
Check key unlock warning switch.
Check harness and connectors between ECU and
key unlock warning switch, key unlock warning
switch and body ground (See page
IN±27).
Replace key unlock warning
switch.1
2
Proceed to next circuit inspection shown on
matrix chart (See page BE±371). Repair or replace harness or
connector.
WIRING DIAGRAM
Key Unlock Warning Switch Circuit
CIRCUIT DESCRIPTION
The key unlock warning switch goes on when the ignition key is inserted in the key cylinder and goes
off when the ignition key is removed.
The ECU operates the key confinement prevention function while the key unlo\
ck warning switch is on.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BE±388±
BODY ELECTRICAL SYSTEM Door Lock Control System
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