Lexus SC300 / Lexus SC400. Service manual — part 51

1

(1)

Turn ignition switch LOCK.

(2)

Disconnect negative (–) terminal cable from
battery.

(3)

Disconnect center airbag sensor assembly
connector.

(4)

Connect negative (–) terminal cable to battery.

Does airbag warning light turn off?

Check airbag warning light circuit or terminal
AB circuit of TDCL or check connector.

NG

YES

Check operation of airbag warning light.

Replace center airbag sensor assembly.

INSPECTION PROCEDURE

–

SRS AIRBAG

Troubleshooting

AB–85

NG

Check voltage between terminals Tc and E

1

of TDCL or check connector.

OK

1

2

3

1

NG

NG

NG

OK

OK

OK

3

Check voltage between terminal Tc of TDCL
or check connector and body ground.

Check center airbag sensor assembly.

Replace center airbag sensor assemly.

Check resistance between terminal Tc of
center airbag sensor assembly and body
ground.

HINT:

If the diagnostic code is continuously displayed, perform the following troubleshooting:

Repair or replace harnes or connector.

Replace center airbag sensor
assembly.

Check harness between center
airbag sensor assembly and
TDCL or check connector.

Check harness between terminal
E

1

of TDCL or check connector

and body ground.

Go to step

Tc Terminal Circuit

CIRCUIT DESCRIPTION

By connecting terminals Tc and E of the TDCL or check connector, the center airbag sensor assembly
is set in the diagnostic code output mode. The diagnostic codes are displayed by the blinking of the
airbag warning light.

DIAGNOSTIC CHART

Troubleshooting for this system is different depending on whether the diagnostic code is not displayed
or is continuously displayed. Confirm the problem symptoms first before selecting the appropriate
troubleshooting procedure.
HINT: If the diagnostic code is not displayed, perform the following troubleshooting:

AB–86

–

SRS AIRBAG

Troubleshooting

WIRING DIAGRAM

DIAGNOSTIC CHART

–

SRS AIRBAG

Troubleshooting

AB–87

INSPECTION PROCEDURE

HINT: If the diagnostic code is not displayed, perform the following troubleshooting:

Check voltage between terminals Tc and E

1

of TDCL or check connector.

nector

Turn ignition switch ACC or ON.

Measure voltage between terminals Tc and E

1

of

TDCL or check connector.

Voltage: 10 – 14 V

Measure voltage between terminal Tc of TDCL or
check connector and body ground.

Voltage: 10 – 14 V

Check harness between terminal E1 of TDCL
or check connector and body ground

Check voltage between terminals Tc or TDCL or check connector and
body ground.

AB–88

–

SRS AIRBAG

Troubleshooting