Lexus SC300 / Lexus SC400. Manual - part 67

(1) Turn ignition switch LOCK.
(2) Disconnect negative (–) terminal cable from

battery.

(3) Connect connector to center airbag sensor

assembly.

(4) Using a service wire, Connect D

+

 and D

–

 on

spiral cable side of connector between spiral
cable and steering wheel pad.

(5) Connect negative (–) terminal cable to battery,

and wait at least 2 seconds.

Check squib circuit.

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

Measure voltage at D

+

 on spiral cable side of con-

nector between spiral cable and steering wheel
pad.

Go to step [ 7 ].

Resistance:  1 V

Replace center airbag sensor assembly.

Check center airbag sensor assembly.

(1) Turn ignition switch ACC or ON and wait at

least 20 seconds.

(2) Using SST, connect terminals Tc and E

1

 of

TDCL.
SST 09843–18020

(3) Check diagnostic code.

Diagnostic code 12 is not output.

AB–51

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 AIRBAG   –   Troubleshooting

(1) Turn ignition switch LOCK.
(2) Disconnect battery negative (–) terminal cable,

and wait at least 20 seconds.

(3) Connect steering wheel pad (squib) connector.
(4) Connect negative (–) terminal cable to battery,

and wait at least 2 seconds.

Check squib.

Measure voltage at D

+

 on spiral cable side of con-

nector between spiral cable and steering wheel
pad.

Repair or replace spiral cable.

Diagnostic code 12 is not output.

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.

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

Check spiral cable.

(1) Turn ignition switch ACC or ON, and wait at

least 20 seconds.

(2) Using SST, connect terminals Tc and E

1

 of

TDCL.
SST 09843–18020

(3) Check diagnostic code.

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

Voltage:  Below 1 V

(1) Turn ignition switch LOCK.
(2) Disconnect connector between center airbag

sensor assembly and spiral cable.

(3) Turn ignition switch ON.

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 AIRBAG   –   Troubleshooting

MEMO

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 AIRBAG   –   Troubleshooting

Diag. Code 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 airbag to deploy when the airbag deployment conditions are satisfied.
For details of the function of each component, see FUNCTION OF COMPONENTS on page 

AB–7

.

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

Code 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

Preparation.

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.

Check squib circuit.

Check center airbag sensor assembly.

Check squib.

Go to step [ 5 ] on next page.

Replace center airbag sensor
assembly.

Replace steering wheel pad.

AB–54

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 AIRBAG   –   Troubleshooting