sensor LEXUS SC400 1991 Service Repair Manual

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OKNG
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.
5Check spiral cable.
C
OK
P1. Disconnect connector between center airbag sen-sor assembly and spiral cable.
2. Release airbag activation prevention mechanism on center airbag sensor assembly side of spiral
cable connector (See page RS±91).
Measure resistance between D
+ and D± on spiral cable
side of connector between spiral cable and steering
wheel pad.
Resistance: 1 M
or higher
Repair or replace spiral cable.
6Check harness between center airbag sensor assembly and spiral cable.
C
OK
P1. Disconnect center airbag sensor assembly con-
nector.
2. Release airbag activation prevention mechanism on center airbag sensor assembly connector (See
page RS±91 ).
Measure resistance between D
+ and D± on center air-
bag sensor assembly side of connector between center
airbag sensor assembly and spiral cable.
Resistance: 1 M
or higher.
Repair or replace harness or connector between center
airbag sensor assembly and spiral cable.
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±89
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7Check center airbag sensor assembly.
C
OK
PConnect center airbag sensor assembly connector.
Measure resistance between D
+ and D± on center air-
bag sensor assembly side of connector between center
airbag sensor assembly and spiral cable.
Resistance: 1 k
or more
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±90±
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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±
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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
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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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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±
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DTC15Open in Front Airbag Sensor Circuit
CIRCUIT DESCRIPTION
The front airbag sensor detects the deceleration force in a frontal collisi\
on and is located in the front fender on
the left and right sides.
For details of the function of each component, see FUNCTION OF COMPONENTS o\
n page RS±10. Diagnostic
trouble code 15 is recorded when an open is detected in the front airbag sensor\
circuit.
NOTICE: The front airbag sensor connector is equipped with an electrical connec\
tion check mechanism
for the purpose of detecting an open in the front airbag sensor (See pa\
ge RS±13). This mechanism is
constructed so that when the terminals of the front airbag sensor have been connect\
ed (when the con-
nector housing lock is in the locked condition), the connection detection pin\
on the wire harness side
connects with the terminals for diagnosis use on the sensor side. If the connector is \
not properly con-
nected, the diagnosis system may detect only a malfunction code, even though the supplemental re-
straint system is functioning normally. When connecting the front airbag sensor connector, make sure
it is connected properly. If diagnostic trouble code 15 is displayed after the front airbag sens\
or connec-
tor has been connected, check again that it is properly connected.
DTC No.Diagnosis
15
 Open circuit in +S wire harness or ±S wire harness of front airbag se\
nsor.
 Front airbag sensor malfunction.
 Malfunction of electrical connection check mechanism of front airbag sen\
sor.
 Center airbag sensor assembly malfunction.
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±97
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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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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±
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OKNG
OKNG
4Check front airbag sensor.
C
OK
PDisconnect front airbag sensor connector.
Measure resistance between each terminal of front air-
bag sensor.
Notice:
Do not touch ohmmeter probes strongly against
terminals of front airbag sensor.
 Make sure the front airbag sensor connector is
properly connected.
Replace front airbag sensor.
5Check harness between center airbag sensor assembly and front airbag sen\
sor.
C
OK
P5. Disconnect center airbag sensor assembly con- nector.
6. Using service wires, connect +SR and ±SR, +SL and ±SL on the wire harness side of the center air-
bag sensor assembly connector.
Measure resistance between terminals +SR and ±SR,
+SL and ±SL of harness side connector of front airbag
sensor.
Notice:
 Lightly t ouch ohmmeter proves at position shown
in illustration.
 Make sure the front airbag sensor connector is
properly connected.
Resistance: Below 1

Repair or replace harness or connector between center
airbag sensor assembly and front airbag sensor. (See
page RS±48 ).
Replace front airbag sensor connector (See page RS±48).
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±101
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