Lexus SC300 / Lexus SC400. Service manual — part 65

DIAGNOSTIC CHART (Cont’d)

Check front airbag sensor.

Replace front airbag sensor.

Repair or replace spiral cable.

Check spiral cable.

Repair or replace harness or connector
between center airbag sensor assembly and
front airbag sensor (See page

AB–20

).

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

WIRING DIAGRAM

AB–43

SRS

AIRBAG – Troubleshooting

(1) Disconnect battery negative (–) terminal cable,

and wait at least 20 seconds.

(2) Remove steering wheel pad (See page

AB–16

).

Check front airbag sensor circuit. (Measure resistance between terminals +SR and
–SR, +SL and –SL of center airbag sensor assembly connector.

Preparation.

Disconnect center airbag sensor assembly con-
nector.

Measure resistance between terminals +SR and
–SR, +SL and –SL of harness side connector of
center airbag sensor assembly.

Go to step [ 7 ].

When storing steering wheel pad, keep upper
surface of the pad facing upward.

Resistance: 755

– 855

Check front airbag sensor circuit. (Measure resistance between terminals +SR and
+SL of center airbag sensor assembly connector and body ground.

Measure resistance between terminals +SR, +SL
of harness side connector of center airbag sensor
assembly and body ground.

Repair or replace harness or connector
between center airbag sensor assembly

and front airbag sensor (See page

AB–20

).

Resistance: 1 M

or higher

INSPECTION PROCEDURE

AB–44

SRS

AIRBAG – Troubleshooting

(1) Connect connector to center airbag sensor

assembly.

(2) Using a service wire, connect D

+

, D

–

on spiral

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

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

and wait at least 2 seconds.

Check squib circuit.

Codes other than code 11 may be output at this
time, but this is not relevant.

Measure resistance between D

+

, D

–

on spiral cable

side of connector between spiral cable and steer-
ing wheel pad and body ground.

Go to step [ 8 ].

Diagnostic code 11 is not output.

Resistance: 1 M

or higher

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.

AB–45

SRS

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.

Disconnect front airbag sensor connector.

Measure resistance between each terminal of
front airbag sensor.

Replace front airbag sensor.

Diagnostic code 11 is not output.

Replace steering wheel pad.

•

Do not touch ohmmeter probes strongly against
terminals of front airbag sensor.

•

Make sure the front airbag sensor connector is
properly connected.

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 front airbag

sensor (See page

AB–20

).

Check front airbag sensor.

(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 11 may be output at this
time, but this is not relevant.

AB–46

SRS

AIRBAG – Troubleshooting