Lexus SC300 / Lexus SC400. Service manual — part 47

Preperation.

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

Check center airbag sensor assembly.

From the results of the above inspection, the
malfunctioning part can now be considered nor-
mal. To make sure of this, use the simulation
method to check.

Check front airbag sensor.

Check harness between center airbag
sensor assembly and front airbag sensor.

Replace front airbag sensor connector
(See page

AB–20

).

Replace center airbag sensor
assembly.

Go to step

Replace front airbag sensor.

Repair or replace harness or con-
nector between center airbag sen-
sor assembly and front airbag sen-
sor (See page

AB–20

).

WIRING DIAGRAM

DIAGNOSTIC CHART

DIAGNOSTIC CHART

–

SRS AIRBAG

Troubleshooting

AB–69

INSPECTION PROCEDURE

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

Preparation.

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

and wait at least 20 seconds.

(2) Remove steering wheel pad

(See page

AB–14

).

Disconnect center airbag sensor assembly connector.

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

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

Resistance: 755

– 885

Go to step

AB–70

–

SRS AIRBAG

Troubleshooting

3

Codes other than code 15 may be output at this
time, but this is not relevant to this check.

Replace front airbag sensor.

NG

OK

(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.

Check center airbag sensor assmbly.

Check front airbag sensor.

Replace center airbag sensor assembly.

NG

OK

Diagnostic code 15 is not output.

(1)

Connect connector to center airbag sensor
assembly.

(2)

Using a service wire, connect D+ and 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.

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.

4

Disconnect front airbag sensor connector.

Measure resistance between each terminal of
front airbag sensor.

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

Make sure the front airbag sensor connector
is properly connected.

Terminal

Resistance

Below 1

755

–885

1 M

or higher

+S – +A

+S – –S

–S – –A

–

SRS AIRBAG

Troubleshooting

AB–71

5

Check harness between center airbag sensor assembly and front airbag
sensor.

(1)

Disconnect center airbag sensor assembly
connector.

(2)

Using service wires, connect +SR and –SR,
+SL and –SL on the wire harness side of the
center airbag sensor assembly connector.

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

Lightly touch ohmmeter probes at
position shown in illustration.

Make sure the front airbag sensor con-
nector is properly connected.

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

sensor (See page

AB–20

).

Replace front airbag sensor connector (See page

AB–20

)

NG

OK

Resistance: Below 1

AB–72

–

SRS AIRBAG

Troubleshooting