Lexus SC300 / Lexus SC400. Manual - part 50

1

NG

OK

(1)

Turn ignition switch LOCK, and wait at least 20 
seconds.

(2)

Turn ignition switch ACC or ON, and wait at least 20
seconds.

(3)

Repeat operation in step (1) and (2) at least 5 times.

(4)

Using SST, connect terminals Tc and E

1

 of TDCL.

SST 09843–18020

(5)

Check diagnostic code.

Is diagnostic code 31 output again?

Using simulation method, reproduce 

malfunction symptoms (See page 

IN–20

).

Clear malfunction code stored in memory 

(See page 

AB–32

).

Replace center airbag sensor assembly.

INSPECTION PROCEDURE

HINT:When a malfunction code other than code 31 is displayed at the same time, first repair the malfunction

indicated by the malfunction code other than code 31.

–

SRS AIRBAG

Troubleshooting

AB–81

OK

Check operation of airbag warning light.

NG

1

WIRING DIAGRAM

2

Is diagnostic code 41 output again?

System is normal.

Check harness between ECU–B
fuse and center airbag sensor as-
sembly. If normal, replace center
airbag sensor assembly.

Perform troubleshooting according to
malfunction code output.

NO

YES

Diag. Code 41

Malfunction Stored in Memory

      CIRCUIT DESCRIPTION

If a malfunction occurs in the airbag system, malfunction codes 11 to 31 may be output, and when the
battery is disconnected after the malfunction is repaired, malfunction codes 11 to 31 will be cleared,
but code 41 will be output instead.
So long as the cancellation operation for a malfunction stored in memory (See page

AB–32

) is not per-

formed, code 41 is stored in the center airbag sensor assembly and the airbag warning light remains
lit up.

Code No.

Diagnosis

41

 

Malfunction recorded in memory.

41

 

Center airbag sensor assembly malfunction.

      DIAGNOSTIC CHART

AB–82

–

SRS AIRBAG

Troubleshooting

Clear malfunction code 41 stored in memory

(See page 

AB–32

).

Check operation of airbag warning light.

NG

OK

1

Airbag warning light turns off.

(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)

Check operation of airbag warning light.

System is normal.

2

Is diagnostic code 41 output again?

(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 harness between ECU–B fuse and center
airbag sensor assembly. If normal, replace
center airbag sensor assembly.

Perform troubleshooting according to malfunction code output.

NG

OK

INSPECTION PROCEDURE

–

SRS AIRBAG

Troubleshooting

AB–83

YES

Does airbag warning light turn off?

NO

1

Replace center airbag sensor assembly.

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

WIRING DIAGRAM

Airbag Warning Light System (Always Lit Up)

      CIRCUIT DESCRIPTION

The airbag warning light is located on the combination meter.
When the airbag system is normal, the airbag warning light lights up for approx. 6 seconds after the
ignition switch is turned from LOCK position to ACC or ON position, and then turns off automatically.
If there is a malfunction in the airbag system, the airbag warning light lights up to inform the driver of
the abnormality.
When terminals Tc and E of the TDCL are connected, the diagnostic code is displayed by the blinking
of the airbag warning light.

      DIAGNOSTIC CHART

AB–84

–

SRS AIRBAG

Troubleshooting