Lexus SC300 / Lexus SC400. Service manual — part 54

CONFIRM FUNCTIONING OF SST

When deploying the airbag, always use the specified SST:
SRS AIRBAG DEPLOYMENT TOOL.
SST 09082–00700

1.

CONNECT SST TO BATTERY
Connect the red clip of the SST to the battery positive (+) ter-
minal and the black clip to the battery negative (–) terminal.
HINT: Do not connect the yellow connector which connects
with the airbag system.

2.

CONFIRM FUNCTIONING OF SST
Press the SST activation switch, and confirm the LED of the
SST activation switch lights up.
CAUTION: If the LED lights up when the activation switch
is not being pressed, SST malfunction is probable, so
definitely do not use the SST.

–

SRS AIRBAG

Disposal of Steering Wheel Pad (with Aribag)

AB–97

SERVICE SPECIFICATIONS

SERVICE DATA

Terminal

Front airbag sensor resistance

S –

A

755–885

S

A

S –

S

755 885

S –

A

Less than 1

TORQUE SPECIFICATIONS

Part tightened

N

⋅

m

kgf

⋅

cm

ft

⋅

lbf

Steering wheel

35

360

26

Steering wheel
Steering wheel pad

35

7.4

360

75

26

65 in.

⋅

lbf

g

Front airbag sensor

25

260

19

g

Center airbag sensor assembly

13

130

9

AB–98

–

SRS AIRBAG

Disposal of Steering Wheel Pad (with Airbag)

SRS

AIRBAG

AB–1

INTRODUCTION

GENERAL DESCRIPTION

The LEXUS SC400 is equipped with an SRS (Supplemental Restraint System) airbag.
Failure to carry out service operations in the correct sequence could cause the airbag system to unex-
pectedly deploy during servicing, possibly leading to a serious accident.
Further, if a mistake is made in servicing the airbag system, it is possible the airbag may fail to operate
when required.
Before performing servicing (including removal or installation 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 airbag system are difficult to confirm, so the diagnostic codes become the
most important source of information when troubleshooting.
When troubleshooting the airbag system, always inspect the diagnostic codes before disconnecting the
battery (See page

AB–25

).

2.

Work must be started after approx. 20 seconds or longer from the time the ignition switch is turned
to the LOCK position and the negative (–) terminal cable is disconnected from the battery. (The
airbag system is equipped with a back–up power source so that if work is started within 20 seconds
of disconnecting the negative (–) terminal cable of the battery, the airbag may be deployed.)
When the negative (–) terminal cable is disconnected from the battery, memory of the clock and audio sys-
tems will be cancelled. So before starting work, make a record of the contents memorized by the audio
memory system. Then 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 customer, 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 airbag does not deploy, the front airbag sensors and
the steering wheel pad should be inspected (See page

AB–9

).

4.

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

5.

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

6.

Never disassemble and repair the front airbag sensors, center airbag sensor assembly or steering
wheel pad in order to reuse it.

7.

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

8. Do not expose the front airbag sensors, center airbag sensor assembly or steering wheel pad

directly to hot air or flames.

9.

Use a volt/ohmmeter with high impedance (10 kW/V minimum) for troubleshooting of the electrical
circuit.

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

on the notices.

11. After work on the airbag system is completed, perform the airbag warning light check (See page

AB–30

).

AB–2

SRS

AIRBAG – General Description