Lexus SC300 / Lexus SC400. Manual - part 797

OK

NG

OK

NG

7

Check D squib.

C

OK

Hint

P

1.

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 12 is not output.

Codes other than code 12 may be output at this time, but
is not relevant to this check.

Replace steering wheel pad.

8

Check P squib.

C

OK

Hint

P

1.

Turn ignition switch LOCK.

2.

Disconnect battery negative (–) terminal cable, and
wait at least 90 seconds.

3.

Connect front passenger airbag assembly (squib)
connector.

4.

Disconnect steering wheel pad (squib) connector.

5.

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.

4.

Check diagnostic trouble code.

Diagnostic trouble code 12 is not output.

Codes other than code 12 may be output at this time, but
they are not relevant to this check.

Replace center airbag sensor assembly.

–

SUPPLEMENTAL RESTRAINT SYSTEM

TROUBLESHOOTING

RS–83

OK

NG

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.

9

Check spiral cable.

C

OK

P

1.

Turn ignition switch LOCK.

2.

Disconnect connector between center airbag sen-
sor assembly and spiral cable.

3.

Turn ignition switch ON.

Measure voltage at D+ on spiral cable side of connector
between spiral cable and steering wheel pad.

Voltage:

Below 1 V

Repair or replace spiral cable.

Repair or replace harness or connector between center airbag sensor assembly and spiral cable.

RS–84

–

SUPPLEMENTAL RESTRAINT SYSTEM

TROUBLESHOOTING

DTC

13

Short in Squib Circuit (Between D

+

 Wire Harness

and D

–

 Wire Harness

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 satisfied.
For details of the function of each component, see FUNCTION OF COMPONENTS on page 

RS–10

.

Diagnostic trouble code 13 is recorded when a short is detected in the D+ wire harness and D wire harness of
the squib circuit.

DTC No.

Diagnosis

13



Short circuit between D

+

 wire harness and D

–

 wire harness of squib.



Squib malfunction.



Spiral cable malfunction.



Center airbag sensor assembly malfunction.

DIAGNOSTIC CHART

DIAGNOSTIC CHART

–

SUPPLEMENTAL RESTRAINT SYSTEM

TROUBLESHOOTING

RS–85

WIRING DIAGRAM

DIAGNOSTIC CHART

DIAGNOSTIC CHART

RS–86

–

SUPPLEMENTAL RESTRAINT SYSTEM

TROUBLESHOOTING