1991 LEXUS SC400 fuse chart

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)
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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
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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)
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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
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Slide Switch Circuit
CIRCUIT DESCRIPTION
When the power seat control switch is operated, a signal is sent to the ECU and the ECU applies the power
source to the slide motor.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
Check voltage between terminals SDLF,
SLDR of ECU connector and body ground.OK
NG
OK OK
OK
OK NG
NG NG
NG
NG Proceed to next circuit inspection
shown on matrix chart (See page
BE±319
).
Check DOOR fuse. Check for short in all the harness
and components connected to the
DOOR fuse (See attached wiring
diagram). *
1
Check voltage between terminals B1 and E1
of power seat control switch connector.
Check continuity between terminal E1 of pow-
er seat switch connector and body ground. Repair or replace harness and
connector.
Check harness and connector between
battery and ECU.
Check power seat control switch. Replace power seat control
switch.
Check harness and connector between
power seat control switch and ECU. Repair or replace harness and
connector.
Check and replace ECU. *
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 fusible link may become open, so
also inspect the actuator.
(Slide motor circuit on page
BE±328).
BE±334±
BODY ELECTRICAL SYSTEM Power Seat Control System (Passenger's Seat)
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WIRING DIAGRAM
NGOK
*1 The 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 fusible link may become OPEN, so
also inspect the actuator.
(Slide motor circuit on page BE±328).
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals SLDF, SLDR, of ECU connector and body ground.
C
OK
PRemove ECU with connector still connected.
Measure voltage between SLDF, SLDR terminal and
body ground, when slide switch is operated.
Switch condition Voltage (V)
SLDF SLDR
Forward
Back 10 ± 14 V Below 1 V
Below 1 V 10 ± 14 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±319).
2Check DOOR fuse.
Check for short in all the harness and components con-
nected to the DOOR fuse and repair them (See attached
wiring diagram). *1
Go to step [3].
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Passenger's Seat)BE±335
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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
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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
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