Lexus SC300 / Lexus SC400. Service manual — part 773

OK

NG

OK

NG

3

Check center airbag sensor assembly.

C

OK

Hint

P

1.

Connect negative (–) terminal cable to battery.

2.

Clear malfunction code stored in memory. (See
page

RS–63

).

1.

Turn ignition switch LOCK, and wait at least 20 sec-
onds.

2.

Using a service wire, connect D

+

and D

–

, P

+

and P

–

.

3.

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

4.

Using SST, connect terminals Tc and E

1

of DLC2.

SSt 09843–18020

5.

Check diagnostic trouble code.

Diagnostic trouble code 53 is not output.

Codes other than code 53 may be output at this time, but
this is not relevant to this check.

Replace center airbag sensor assembly.

4

Check P squib.

C

OK

Hint

P

1.

Turn ignition switch LOCK.

2.

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

3.

Connect front passenger airbag assembly connec-
tor.

4.

Connect negative (–) terminal cable to battery.

5.

Clear malfunction code.

1.

Turn ignition switch LOCK, and wait at least 20 sec-
onds.

2.

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

3.

Using SST, connect terminals Tc and E

1

of DLC2.

SST 09843–18020

4.

Check diagnostic trouble code.

Diagnostic trouble code 53 is not output.

Codes other than code 53 may be output at this time, but
this is not relevant to this check.

Replace front passenger airbag assembly.

–

SUPPLEMENTAL RESTRAINT SYSTEM

TROUBLESHOOTING

RS–113

OK

NG

OK

NG

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.

5

Check P circuit.

C

OK

P

1.

Disconnect center airbag sensor assembly con-
nector.

2.

Release airbag activation prevention mechanism
on center airbag sensor assembly connector (See
page

RS–91

).

Measure resistance between P

+

and P

–

on center air-

bag sensor assembly side of connector between airbag
sensor assembly and front passenger airbag assembly.

Resistance:

1 M

of higher

Repair or replace harness or connector between center
airbag sensor assembly and front passenger airbag as-
sembly.

6

Check center airbag sensor assembly.

C

OK

P

Connect center airbag sensor assembly connector.

Measure resistance between P

+

and P

–

on center air-

bag sensor assembly side of connector between center
airbag sensor assembly and front passenger airbag as-
sembly.

Resistance:

1 k

or higher

Replace center airbag sensor assembly.

From the results of the above inspection, the malfunction part can now be considered normal. To make
sure of this, use the simulation method to check.

RS–114

–

SUPPLEMENTAL RESTRAINT SYSTEM

TROUBLESHOOTING

DTC

54

Open in P Squib Circuit

CIRCUIT DESCRIPTION

The squib circuit consists of the center airbag sensor assembly and front passenger airbag assembly. It causes
the SRS to deploy when the SRS deployment conditions are satisfied. For details of the function of each compo-
nent, see FUNCTION OF COMPONENTS on page

RS–10

.

Diagnostic trouble code 54 is recorded when an open is detected in the squib circuit.

DTC No.

Diagnosis

54

Open circuit in P

+

wire harness and P

–

wire harness of squib.

Squib malfunction.

Center airbag sensor malfunction.

–

SUPPLEMENTAL RESTRAINT SYSTEM

TROUBLESHOOTING

RS–115

WIRING DIAGRAM

DIAGNOSTIC CHART

DIAGNOSTIC CHART

RS–116

–

SUPPLEMENTAL RESTRAINT SYSTEM

TROUBLESHOOTING