Lexus ES300 (1997 year). Service manual — part 390

R16017

Airbag Sensor Assembly

P Squib

D Squib

Spiral
Cable

1

2

1

2

2

P+

P–

D+

D–

3

6

7

Y–R

Y–B

Y–G

Y

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

DI–337

489

1997 LEXUS ES300 (RM511U)

DTC

12

Short in Squib Circuit (to B+)

CIRCUIT DESCRIPTION

The squib circuit consists of the airbag sensor assembly, spiral cable, steering wheel pad and front passen-
ger airbag assembly.
It causes the SRS to deploy when the SRS deployment conditions are satisfied.
For details of the function of each components, see page OPERATION on page

RS–2

.

DTC 12 is recorded when a B+ short is detected in the squib circuit.

DTC No.

DTC Detecting Condition

Trouble Area

12

Short circuit in squib wire harness (to B+)

Squib malfunction

Spiral cable malfunction

Airbag sensor assembly malfunction

Steering wheel pad (D squib)

Front passenger airbag assembly (P squib)

Spiral cable

Airbag sensor assembly

Wire harness

WIRING DIAGRAM

DI0B1–01

AB0119

W01931

R14288

H00055

Airbag Sensor
Assembly

Spiral
Cable

ON

P Squib

D Squib

D+

(+)

(–)

R05898

AB0119

R14288

H00056

ON

P+

(+)

(–)

Airbag Sensor
Assembly

P Squib

D Squib

Spiral
Cable

DI–338

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

490

1997 LEXUS ES300 (RM511U)

INSPECTION PROCEDURE

1

Preparation. (See step ” 1 ” on page

DI–359

)

2

Check D squib circuit.

CHECK:
For the connector (on the spiral cable side) between the spiral
cable and steering wheel pad, measure the voltage between
D+ and body ground.
OK:

Voltage: 0 V

NG

Go to step ” 7 ”.

OK

3

Check P squib circuit.

CHECK:
For the connector (on the airbag sensor assembly side) be-
tween airbag sensor assembly and front passenger airbag as-
sembly, measure the voltage between P+ and body ground.
OK:

Voltage: 0V

AB0069

AB0069

AB0118

R13006

AB0119

W01933

W02043

H00012

Airbag Sensor
Assembly

P+

P–

Spiral
Cable

P Squib

D Squib

D–

D+

ACC

ON

or

DLC1

Code 12

E1

Tc

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

DI–339

491

1997 LEXUS ES300 (RM511U)

NG

Repair or replace harness or connector be-
tween the airbag sensor assembly and front
passenger airbag assembly.

OK

4

Check airbag sensor assembly.

PREPARATION:
(a)

Connect connector to airbag sensor assembly.

(b)

Using a service wire, connect D+ and D– on spiral cable
side of connector between spiral cable and steering
wheel pad.

(c)

Using a service wire, connect P+ and P– on airbag sensor
assembly side of connector between airbag sensor as-
sembly and front passenger airbag assembly.

(d)

Connect negative (–) terminal cable to battery, and wait
at least 2 seconds.

CHECK:
(a)

Turn ignition switch to ACC or ON and wait at least 20 se-
conds.

(b)

Clear malfunction code stored in memory
(See page

DI–324

).

(c)

Turn ignition switch to LOCK, and wait at least 20 se-
conds.

(d)

Turn ignition switch to ACC or ON, and wait at least 20 se-
conds.

(e)

Using SST, connect terminals Tc and E1 of DLC1.
SST 09843–18020

(f)

Check DTC.

OK:

DTC 12 is not output.

HINT:Codes other than code 12 may be output at this time, but
they are not relevant to this check.

NG

Replace airbag sensor assembly.

OK

R13006

R05896
AB0118 AB0019

W02043

H00013

Airbag Sensor
Assembly

P Squib

D Squib

Spiral
Cable

ACC

ON

or

DLC1

Code 12

E1

Tc

DI–340

–

DIAGNOSTICS

SUPPLEMENTAL RESTRAINT SYSTEM

492

1997 LEXUS ES300 (RM511U)

5

Check D squib.

PREPARATION:
(a)

Turn ignition switch to LOCK.

(b)

Disconnect negative (–) terminal cable from the battery,
and wait at least 90 seconds.

(c)

Connect steering wheel pad connector.

(d)

Connect negative (–) terminal cable to battery, and wait
at least 2 seconds.

CHECK:
(a)

Turn ignition switch to ACC or ON, and wait at least 20 se-
conds.

(b)

Clear malfunction code stored in memory
(See page

DI–324

).

(c)

Turn ignition switch to LOCK, and wait at least 20 se-
conds.

(d)

Turn ignition switch to ACC or ON, and wait at least 20 se-
conds.

(e)

Using SST, connect terminals Tc and E1 of DLC1.
SST 09843–18020

(f)

Check DTC.

OK:

DTC 12 is not output.

HINT:Codes other than code 12 may be output at this time, but
they are not relevant to this check.

NG

Replace steering wheel pad.

OK