ect LEXUS SC300 1991 Service Repair Manual

LOCATION OF CONNECTORS
LOCATION OF CONNECTORS IN ENGINE COMPARTMENT
SC400
SR±54±
STEERING STEERING COLUMN
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LOCATION OF CONNECTORS IN BODY
SR±56±
STEERING STEERING COLUMN
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LOCATION OF CONNECTORS IN INSTRUMENT PANEL
SR±58±
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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DTC53Short in Squib Circuit (Between P+ Wire Harness
P
± Wire Harness)
CIRCUIT DESCRIPTION
The squib circuit consists of the center airbag sensor assembly, (squib). It causes the SRS to deploy when the
SRS deployment conditions are satisfied.
For details of the function of each component, see FUNCTION OF COMPONENTS o\
n page RS±10. Diagnostic
trouble code 53 is recorded when an short is detected in the P
+ wire harness and P± wire harness of the squib
circuit.
DTC No.Diagnosis
53
 Short circuit between P+ wire harness and P± wire harness of squib.
 Squib malfunction.
 Center airbag Sensor Assembly malfunction.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
RS±110±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTING
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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
OKNG
3Check center airbag sensor assembly.
C
OK
Hint
P1. Connect negative (±) terminal cable to battery.
2. Clear malfunction code stored in memory. (Seepage RS±63 ).
1. Turn ignition switch LOCK, and wait at least 20 sec- onds.
2. Using a service wire, connect D
+ and D±, P+ and P±.
3. Turn ignition switch ACC or ON, and wait at least 20 seconds.
4. Using SST, connect terminals Tc and E
1 of DLC2.
SSt 09843±18020
5. Check diagnostic trouble code.
Diagnostic trouble code 53 is not output.
Codes other t han code 53 may be output at this time, but
this is not relevant to this check.
Replace center airbag sensor assembly.
4Check P squib.
C
OK
Hint
P1. Turn ignition switch LOCK.
2. Disconnect battery negative (±) terminal cable, and
wait at least 90 seconds.
3. Connect front passenger airbag assembly connec- tor.
4. Connect negative (±) terminal cable to battery.
5. Clear malfunction code.
1. Turn ignition switch LOCK, and wait at least 20 sec- onds.
2. Turn ignition switch ACC or ON, and wait at least 20 seconds.
3. Using SST, connect terminals Tc and E
1 of DLC2.
SST 09843±18020
4. Check diagnostic trouble code.
Diagnostic trouble code 53 is not output.
Codes other t han code 53 may be output at this time, but
this is not relevant to this check.
Replace front passenger airbag assembly.
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±113
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