1991 LEXUS SC400 steering wheel

DTC14Open in D Squib Circuit
CIRCUIT DESCRIPTION
The squib circuit consists of the center airbag sensor assembly, spiral cable and the steering wheel pad (squib).
It causes the SRS to deploy when the SRS deployment conditions are satisfi\
ed.
For details of the function of each component, see FUNCTION OF COMPONENTS o\
n page RS±9. Diagnostic
trouble code 14 is recorded when an open is detected in the squib circuit.
DTC No.Diagnosis
14
 Open circuit in D+ wire harness or D± wire harness of squib.
 Squib malfunction.
 Spiral cable malfunction.
 Center airbag sensor assembly malfunction.
RS±92±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTING
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NGOK
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 D squib circuit.
C
OK
PDisconnect center airbag sensor assembly connector.
Measure resistance between D+ and D± on spiral cable
side of connector between spiral cable and steering
wheel pad.
Resistance: Below 1

Go to Step
.
RS±94
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTING
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OKNG
OKNG
3Check spiral cable.
C
OK
PDisconnect connector between center airbag sensor
assembly and spiral cable.
Measure resistance between D
+ and D± on spiral cable
side of connector between spiral cable and steering
wheel pad.
Resistance: Below 1

Repair or replace spiral cable.
4Check harness between center airbag sensor assembly and spiral cable.
C
OK
Measure resistance between D+ and D± on center air-
bag sensor assembly side of connector between center
airbag sensor assembly and spiral cable.
Resistance: Below 1

Repair or replace harness or connector between center
airbag sensor assembly and spiral cable.
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±95
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OKNG
OKNG
5Check center airbag sensor assembly.
C
OK
Hint
P1. Connect connector to center airbag sensor connec-
tor.
2. Connect connector between center airbag sensor assembly and spiral cable.
3. Using a service, wire, connect D
+ and D±. P+ and
P±.
4. Connect negative (±) terminal cable to battery and wait at least 2 second.
1. turn ignition switch ACC or ON, and wait at least 20
seconds.
Clear malfunction code. Turn ignition switch LOCK
and wait at least 20 seconds.
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 14 is not output.
Codes other than code 14 may be output at this time ,
but this is not relevant to this check.
Replace center airbag sensor assembly.
6Check D squib.
C
OK
Hint
P1. Turn ignition switch LOCK.
2. Disconnect battery negative (±) terminal cable, and wait at least 90 seconds.
3. Connect steering wheel pad (squib) connector.
4. Connect negative (±) terminal cable to battery, and wait at least 2 seconds.
1. Turn ignition switch ACC or ON, and wait at least 20
seconds.
Clear malfunction code. Turn ignition switch LOCK
and wait at least 20 seconds.
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 14 is not output.
Codes other t han code 14 may be output at this time, but
this is not relevant to this check.
Replace steering wheel pad.
From the results of the above inspection, the malfunctioning part can now be\
considered normal. To
make sure of this, use the simulation method to check.
RS±96±
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 front airbag sensor circuit (Measure resistance between terminals +SR \
and ±SR, +SL
and ±SL of center airbag sensor assembly connector.)
C
OK
PDisconnect center airbag sensor assembly connector.
Measure resistance between terminals +SR and ±SR,
+SL and ±SL of harness side connector of center airbag
sensor assembly.
Resistance: 755
± 885

Go to step
.
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±99
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OKNG
3Check center airbag sensor assembly.
C
OK
Hint
P1. Connect connector to center airbag sensor assem-bly.
2. Using a service wire, connect D+ and D± on spiral cable side of connector between spiral cable and
steering wheel pad.
3. Using a service wire, connect P+ and P±n on center
airbag sensor assembly side of connector between
center airbag sensor assembly and front passen-
ger airbag.
4. Connect negative (±) terminal cable to battery, and wait at least 2 seconds.
1. Turn ignition switch AAC or ON, and wait at least 20 seconds.
Clear malfunction code. Turn ignition switch LOCK
and wait at least 20 seconds.
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 15 is not output.
Code other than code 15 may be output at this time, but
this is not relevant to this check.
Replace center airbag sensor assembly.
From the results of the above inspection, the malfunctioning part can now be\
considered normal. To
make sure of this, use the simulation method to check.
RS±100±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTING
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OKNG
OKNG
INSPECTION PROCEDURE
HINT: If SRS warning light does not light up, perform the following troublesh\
ooting:
1Check ECU±B fuse.
Go to step

2Preparation.
P1. Disconnect battery negative (±) terminal cable, and
wait 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.
3Check connection of center airbag sensor assembly connector.
Repair.
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±105
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4. CHECK WHEEL BEARING LOOSENESS
(a) Check the backlash in bearing shaft direction.
Maximum: 0.05 mm (0.0020 in.)
(b) Check the axle hub deviation.
Maximum: 0.05 mm (0.0020 in.)
5. CHECK FRONT SUSPENSION FOR LOOSENESS
6. CHECK STEERING LINKAGE FOR LOOSENESS
7. CHECK BALL JOINT FOR EXCESSIVE LOOSENESS
8. CHECK SHOCK ABSORBER WORK PROPERLYwCheck for oil leak
w Check mounting busings for wear
w Bounce front and rear of the vehicle
SA±4
±
SUSPENSION AND AXLE GENERAL INSPECTION
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