Lexus SC300 / Lexus SC400. Service manual — part 68

DIAGNOSTIC CHART (Cont’d)

Check spiral cable.

Repair or replace spiral cable.

Check harness between center airbag
sensor assembly and spiral cable.

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

Check center airbag sensor assembly.

Replace center airbag sensor
connector.

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.

WIRING DIAGRAM

AB–55

SRS

AIRBAG – Troubleshooting

INSPECTION PROCEDURE

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

and wait at least 20 seconds.

(2) Remove steering wheel pad (See page

AB–14

).

Preparation.

Measure resistance between D

+

and D

–

on spiral

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

Go to step [ 5 ].

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

Resistance: 1 k

or higher

Check squib circuit.

AB–56

SRS

AIRBAG – Troubleshooting

(1) Connect negative (–) terminal cable to battery.
(2) Clear malfunction code 41 stored in memory

(See page

AB–32

).

Check center airbag sensor assembly.

Replace center airbag sensor assembly.

(1) Turn ignition switch LOCK, and wait at least 2

seconds.

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

least 20 seconds.

(3) Using SST, connect terminals Tc and E

1

of

TDCL.
SST 09843–18020

(4) Check diagnostic code.

Codes other than code 13 may be output at this
time, but this is not relevant to this check.

Diagnostic code 13 is not output.

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

and wait at least 2 seconds.

(3) Connect steering wheel pad (squib) connector.
(4) Connect negative (–) terminal cable to battery.
(5) Clear malfunction code 41 stored in memory

(See page

AB–32

).

Check squib.

Replace steering wheel pad.

Codes other than code 13 may be output at this
time, but this is not relevant to this check.

Diagnostic code 13 is not output.

(1) Turn ignition switch LOCK, and wait at least 2

seconds.

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

least 20 seconds.

(3) Using SST, connect terminals Tc and E

1

of

TDCL.
SST 09843–18020

(4) Check diagnostic code.

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.

AB–57

SRS

AIRBAG – Troubleshooting

(1) Disconnect connector between center airbag

sensor assembly and spiral cable.

(2) Release airbag activation prevention mecha-

nism on center airbag sensor assembly side of

spiral cable connector (See page

AB–60

).

Check squib.

Resistance: 1 M

or higher

Repair or replace spiral cable.

Measure resistance between D

+

and D

–

on spiral

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

(1) Disconnect center airbag sensor assembly

connector.

(2) Release airbag activation prevention mecha-

nism on center airbag sensor assembly connec-

tor (See page

AB–60

).

Check harness 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.

Measure resistance between D

+

and D

–

on center

airbag sensor assembly side of connector between
center airbag sensor assembly and spiral cable.

AB–58

SRS

AIRBAG – Troubleshooting