Lexus SC300 / Lexus SC400. Manual - part 776

NG

OK

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

1

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

C

OK

P

1.

Turn ignition switch LOCK.

2.

Disconnect center airbag sensor assembly con-
nector.

3.

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

4.

Remove steering wheel pad (See page 

RS–19)

.

5.

Disconnect connectors of front passenger airbag
assembly (See page 

RS–32)

.

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

Resistance:

1 M

 or higher

Replace center airbag sensor assembly.

Repair or replace harness or connector.

–

SUPPLEMENTAL RESTRAINT SYSTEM

TROUBLESHOOTING

RS–125

SERVICE SPECIFICATIONS

SERVICE DATA

RS02S–01

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

FRONT AIRBAG SENSOR

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

S – 

A

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

755–855 

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

S – 



S

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

1 M 

 or Higher

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ



S – 



A

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Less than 1 

TORQUE SPECIFICATIONS

RS02T–07

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Part tightened

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

N

⋅

m

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

kgf

⋅

cm

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

ft

⋅

lbf

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Steering wheel

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

35

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

360

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

26

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Steering wheel pad

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

7.4

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

75

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

65 in.

⋅

lbf

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Front passenger airbag assembly

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

21

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

210

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

15

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Front airbag sensor

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

25

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

260

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

19

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Center airbag sensor assembly

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

15

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

150

ÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑ

11

RS–126

–

SUPPLEMENTAL RESTRAINT SYSTEM

SERVICE SPECIFICATIONS

SUPPLEMENTAL RESTRAINT SYSTEM

RS–1

GENERAL DESCRIPTION

The LEXUS SC400/300 is equipped with an SRS (Supplemental Restraint System) such as the driver
airbag and front passenger airbag. Failure to carry out service operations in the correct sequence
could cause the SRS to unexpectedly deployed during servicing, possibly leading to a serious acci-
dent. Further, if a mistake is made in servicing the supplemental restraint system, it is possible the
SRS may fail to operate when required. Before performing servicing (including removal or installa-
tion of parts, inspection or replacement), be sure to read the following items carefully, then follow
the correct procedure described in the repair manual.

1.  Malfunction symptoms of the supplemental restraint system are difficult to confirm, so the diagnostic

trouble codes become the most important source of information when troubleshooting. When
troubleshooting  the supplemental restraint system, always inspect the diagnostic trouble codes before
disconnecting the battery (See page 

RS–59

).

2. 

Work must be started after 90 seconds from the time the ignition switch turned to the LOCK position
and the negative (–) terminal cable is disconnected from the battery. (The supplemental restraint
system is equipped with a back–up power source so that if work is started within 90 seconds of
disconnecting the negative (–) terminal cable of the battery, the SRS may be deployed.)
When the negative (–) terminal cable is disconnected from the battery, memory of the clock and audio sys-
tems will be canceled. So before starting work, make a record of the contents memorized by the audio
memory system. When work is finished, reset the audio systems as before and adjust the clock. When the
vehicle has power tilt and power telescopic steering, power seat, power outside rear view mirror and power
shoulder belt anchorage, which are all equipped with memory function, it is not possible to make a record
of the memory contents. So when the work is finished, it will be necessary to explain this fact to the custom-
er, and ask the customer to adjust the features and reset the memory.
To avoid erasing the memory of each memory system, never use a back–up power supply from outside
the vehicle.

3. 

Even in cases of a minor collision where the SRS does not deploy, the steering wheel pad, front passenger
airbag assembly, front airbag sensors and center airbag sensor assembly should be inspected (See pages

RS–16

, 

28

, 

41

 and 

44

).

4. 

Never use SRS parts from another vehicle. When replacing parts, replace them with new parts.

5. 

Before repairs, remove the airbag sensor if shocks are likely to be applied to the sensors during repairs.

6.  Never disassemble and repair the steering wheel pad, front passenger airbag assembly, front airbag

sensors or center airbag sensor assembly in order to reuse it.

7. 

If the steering wheel pad, front passenger airbag assembly, front airbag sensors or center airbag sensor
assembly have been dropped, or if there are cracks, dents or dents or other defects in the case, bracket
or connector, replace them with new ones.

8. 

Do not expose the steering wheel pad, front passenger airbag assembly, front airbag sensors and center
airbag sensor assembly directly to hot air or flames.

9. 

Use a volt/ohmmeter with high impedance (10 k

/V minimum) of troubleshooting of the system’s electrical

circuit.

10.  Information labels are attached to the periphery of the SRS components. Follow the instructions on the

notices.

11.  After work on the supplemental restraint system is completed, perform the SRS warning light check (See

page 

RS–59

).

12.  If the vehicle is equipped with a mobile communication system, refer to the precaution in the IN section.

RS–2

–

SUPPLEMENTAL RESTRAINT SYSTEM

GENERAL DESCRIPTION