Lexus SC300 / Lexus SC400. Manual — part 62

DIAGNOSTIC CODES

Code

No.

Blink Pattern

Diagnosis

Trouble Area

AIRBAG

Warning Light

(Nor

System normal

–

OFF

(Nor-

mal)

Source Voltage drop

Battery

Center airbag sensor assembly

ON

11

Short in squib circuit
(to ground)

Front airbag sensor
malfunction

Flower sensor malfunction

Steering wheel pad (squib)

Front airbag sensor

Spiral cable

Center airbag sensor assembly

Wire harness

ON

12

Short in squib circuit
(to +B)

Steering wheel pad (squib)

Front airbag sensor

Spiral cable

Center airbag sensor assembly

Wire harness

ON

13

Short in squib circuit
(between D

+

wire harness

and D

–

wire harness)

Steering wheel pad (squib)

Spiral cable

Center airbag sensor assembly

Wire harness

ON

14

Open in squib circuit

Steering wheel pad (squib)

Spiral cable

Center airbag sensor assembly

Wire harness

ON

15

Open in front airbag
sensor circuit

Front airbag sensor

Center airbag sensor assembly

Wire harness

ON

22

Airbag warning light
system malfunction

Airbag warning light

Center airbag sensor assembly

Wire harness

ON

31

Center airbag sensor
assembly malfunction

Center airbag sensor assembly

ON

41

Malfunction stored in
memory

(Center airbag sensor assembly)

ON

HINT:

•

When the airbag warning light remains lit up and the diagnostic code in the normal code, this means a
source voltage drop.
This malfunction is not stored in memory by the center airbag sensor assembly and if the power source
voltage returns to normal, after approx. 10 seconds the airbag warning light will automatically go out.

•

Code 22 in recorded when a malfunction occurs in the airbag warning light system. If an open malfunction
occurs in the airbag warning light system, the airbag warning light does not light up, so that until the
mal–function is repaired, the diagnostic codes (including code 22) cannot be confirmed.

•

When a malfunction occurs in the airbag system, malfunction codes 11 to 31 are output. After repairing
the malfunction indicated by malfunction codes 11 to 31, codes 11 to 31 are cleared from the memory, but
code 41 is output instead. Once the malfunction has been detected, the airbag warning light will remain
lit up until code 41 is cleared, even though the malfunction has been repaired.

•

When 2 or more codes are indicated, the lowest numbered code will appear first.

•

If a code not listed on the chart is displayed, then the center airbag sensor assembly is faulty.

AB–31

SRS

AIRBAG – Troubleshooting

CLEARING OF DIAGNOSTIC CODE

1.

CLEARING OF MALFUNCTION CODE
(EXCEPT CODE 41)
Remove the battery negative (–) terminal or ECU–B fuse for
10 seconds or more with the ignition switch OFF.
NOTICE: When connecting the battery after cancelling
the malfunction code, always do it with the ignition
switch in LOCK position. If the battery is connected with
the ignition switch in ACC or ON position, there are cases
when the diagnosis system does not operate normally.
HINT:

•

Code 41 cannot be cleared by this method.

•

The lower the temperature, the longer the battery
negative (–) terminal must be left off.

•

Other memory systems (clock, audio system) will also
be cancelled out (See page

AB–2

).

2. CLEARING

OF

MALFUNCTION

CODE

41

STORED

IN

MEMORY
(a) Connect service wires to terminals Tc and AB of the

TDCL.

(b) Turn the ignition switch ACC or ON and wait approx. 6

seconds.

(c) Starting with the Tc terminal, apply body ground

alternately to terminal Tc and terminal AB twice each in
cycles of 1.0

±

0.5 seconds. Finally, keep applying body

ground to terminal Tc.

HINT: When alternating between body ground of terminals Tc
and AB release one from body ground while applying it to the
other terminal. The time interval in between must be within
the following conditions. If it is out of the conditions, code 41
will not be cleared.

(d) After several seconds, when the airbag warning light

starts to blink in a 64 msec. cycle, cancellation is
completed.

HINT: This method clears not only code No. 41, but also other
malfunction codes all at once.
Except when instructed by the troubleshooting procedure,
use this method only when the repair procedure is completed
(See page

AB–25

).

AB–32

SRS

AIRBAG – Troubleshooting

Wiring Diagram

CENTER AIRBAG SENSOR ASSEMBLY CONNECTOR

No.

Symbol

Terminal Name

No.

Symbol

Terminal Name

1

8

E

2

Ground

2

–SR

RH Front Airbag Sensor (–)

9

LA

Airbag Warning Light

3

+SR

RH Front Airbag Sensor (+)

10

D

–

Squib (–)

4

+SL

LH Front Airbag Sensor (+)

11

D

+

Squib (+)

5

–SL

LH Front Airbag Sensor (–)

12

Tc

Diagnosis

6

+B

Battery (ECU–B Fuse)

13

E

1

Ground

7

IG

2

Power Source (IGN Fuse)

14

Acc

Power Source (CIG Fuse)

A

L1

Electrical Connection Check
Mechanism

B

L

2

Electrical Connection Check
Mechanism

AB–33

SRS

AIRBAG – Troubleshooting

Diagnostic Code Matrix Chart

If a malfunction code is displayed during the diagnostic code check, check the circuit listed for that code in the
table below (Proceed to the page given for that circuit).

Code No.

Diagnosis

Page

(Normal)*1

Source voltage drop

AB–40

11

Short in squib circuit or front airbag sensor circuit (to ground)

AB–42

12

Short in squib circuit or front airbag sensor circuit (to +B)

AB–48

13

Short in squib circuit (between D+ wire harness and D– wire harness)

AB–54

14

Open in squib circuit

AB–62

15

Open in front airbag sensor circuit

AB–68

22*

2

Airbag warning light system malfunction

AB–74

31

Center airbag sensor assembly malfunction

AB–80

41*

3

Malfunction stored in memory

AB–82

HINT:
*1

When the airbag warning light remains lit up and the diagnostic code is the normal code, this means a
source voltage drop.

*2

Code 22 is recorded when a malfunction occurs in the airbag warning light system. If an open malfunction
occurs in the airbag warning light system, the airbag warning light does not light up, so that until the mal-
function is repaired, the diagnostic code (including code 22) cannot be confirmed.

*3

When a malfunction occurs in the airbag system, malfunction codes 11 to 31 are output. After repairing
the malfunction indicated by malfunction codes 11 to 31, codes 11 to 31 are cleared from the memory, but
code 41 is output instead. Once the malfunction has been detected, the airbag warning light will remain
lit up until code 41 is cleared, even though the malfunction has been repaired.

Problem Symptom Chart

Proceed with troubleshooting of each circuit in the table below.

Problem Symptom

Inspection Item

Page

With the ignition switch at ACC or ON, the airbag warning light
sometimes lights up after approx. 6 seconds have elapsed.

Airbag warning light lights up even when ignition switch is in the
LOCK position.

Airbag warning light system
(Always lit up)

AB–84

Diagnostic code not displayed.

Diagnostic code continuously displayed.

Tc terminal circuit

AB–86

AB–34

SRS

AIRBAG – Troubleshooting