1991 LEXUS SC400 steering

SR±60±
STEERING STEERING COLUMN
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LOCATION OF CONNECTORS IN SEAT
±
STEERING STEERING COLUMNSR±61
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SR±52).
IN±33).
WIRING DIAGRAM
CIRCUIT INSPECTION
ECU Power Source Circuit
CIRCUIT DESCRIPTION
The ECU power source also supplies power to the CPU and sensor, etc. Power is supplied to the ECU even
when the ignition switch is off.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
SR±62±
STEERING STEERING COLUMN
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NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals ECU±B and ECU±E of ECU connector.
C
OK
PRemove ECU with connectors still connected.
Measure voltage between terminals ECU±B and ECU±
E of ECU connector.
Voltage: 10 ~ 14 V
Proceed to next circuit inspection shown on matrix chart
(See page SR±52).
2Check continuity between terminal ECU±E of ECU connector and body gro\
und.
C
OK
Measure resistance between terminal ECU±E of ECU
connector and body ground.
Resistance: 1
or less
Repair or replace harness or connector.
Go to Step
.
±
STEERING STEERING COLUMNSR±63
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OKNG
3Check 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 DOME Fuse (See attached wiring diagram).
Check harness and connector between ECU and
battery (See page
IN±33).
SR±64±
STEERING STEERING COLUMN
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±MEMO±
±
STEERING STEERING COLUMNSR±65
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OKNG
INSPECTION PROCEDURE
1Preparation.
P1. Disconnect battery negative (±) terminal cable, andwait at least 90 seconds.
2. Remove steering wheel pad (See page RS±19).
3. Disconnect connectors of front passenger airbag assembly (See page RS±32).
Caution: Store the steering wheel pad with the
surface facing upward.
2Check P squib circuit.
C
OK
Measure resistance between P+ and P± on center air-
bag sensor assembly side of connector between center
airbag sensor assembly and front passenger airbag as-
sembly.
Resistance: 1 k
or higher
Go to step
.
RS±112
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTING
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OKNG
1Preparation.
P1. Disconnect battery negative (±) terminal cable, andwait at least 90 seconds.
2. Remove steering wheel pad (See page RS±19).
3. Disconnect connectors of front passenger airbag assembly (See page RS±32).
Caution: Store the steering wheel pad with the
surface facing upward.
2Check P squib circuit.
C
OK
PDisconnect center airbag sensor assembly connector.
Measure resistance between P
+ and P± on center air-
bag sensor assembly side of connector between center
airbag sensor assembly and front passenger airbag as-
sembly.
Resistance: Below 1

Repair or replace harness or connector between center
airbag sensor assembly and front passenger airbag as-
sembly.
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±117
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