Lexus SC300 / Lexus SC400. Manual - part 312

Remove weld point and panel position

Weld points

REMOVAL

Weld method and panel position

Weld points

INSTALLATION

SYMBOL

MEANING

ILLUSTRATION

SYMBOL

Spot Weld

MEANING

ILLUSTRATION

Remove
Weld
Points

(Outside)

Mig Plug
Weld

(Middle)

(Inside)

Spot MIG
Weld

HINT: Panel position syrnbols are as seen from the
working posture.

Illustration of Weld Point Symbols

EXAMPLE:

INTRODUCTION

IN-5

Steering Wheel Pad (Airbag and Inflator)

Junction Block No. 1

Center Airbag

Front Airbag Sensor

Front Airbag Sensor

Warning Light

Spiral Cable (in Combination Switch)

HANDLING PRECAUTIONS ON RELATED COMPONENTS

1. SRS AIRBAG

Locations of Airbag Components

This vehicle has an SRS AIRBAG (referred to as the airbag in the remainder of this manual).
When handling airbag components (removal, installation or inspection, etc.), always follow the directions
given in the repair manual for the relevant model year to prevent the occurrence of accidents and airbag
malfunction.
Also take the following precautions when repairing the body:

Work must be started after 20 seconds or longer from the time the ignition switch is set 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
systems will be cancelled. So before starting work, make a record of the contents memorized by each
memory system. Then when work is finished, reset the clock and audio systems as before.
When the vehicle has tilt and telescopic steering, power seat, and outside rear view mirror, which are all
equipped with memory function, it is not possible to make a record of the memory contents.
So when the operation is finished, it will be necessary to explain this fact to the customer, and request
the customer to adjust the features and reset the memory.
To avoid erasing the memory of each memory system, never use back-up power supply from outside
the vehicle.

When using electric welding, first disconnect the airbag connector (yellow color and 2 pins) under the
steering column near the combination switch connector before starting work.

Sensor Assembly

INTRODUCTION

IN-6

Front
Fender Area

Area from the Front Fender Apron 
to the Cowl Side Member

Before repairing the body, remove the airbag sensors if, during repair, shocks are likely to, be applied
to the sensors due to vibrations of the body or direct tapping with tools or other parts.

Do not expose the airbag sensors or the steering wheel pad directly to hot air or flames.

NOTICE:
1)

The maximum ambient temperature tolerance is 120

°

C (248

°

F) for the front airbag sensor, 105

°

C

(221

°

F) for the center airbag sensor assembly and 93

°

C (200

°

F) for the steering wheel pad. If it is

possible that the ambient temperature may reach or exceed the temperature limit, remove the sen-
sors and the steering wheel pad from the vehicle or protect them with a hot insulation material be-
fore starting work.

2)

Prior to welding, remove adjacent airbag sensors or the steering wheel pad from the vehicle or 
protect them with fire-proof covers.

If the front fender or periphery of the vehicle is damaged, visually inspect for damage to the front air-
bag sensor using the inspection procedures described in section AB of the repair manual for the rele-
vant model year.
Also check that the dimensions of the body where the front airbag sensor is installed match those in
the body dimension drawings.
(The airbag may malfunction; or may not work, if the mounting angle or dimensions of the sensor
mount are not correct.)

If the vehicle is damaged, visually inspect for damage to the steering wheel pad using the inspection
procedures described in section AB of the repair manual for the relevant model year.

When removing the steering wheel pad or handling a new steering wheel pad, keep the pad upper
surface facing upward. Also, lock the lock lever of the twin lock type connector at the rear of the pad
and take care not to damage the connector.
(Storing the pad with its metallic surface up may lead to a serious accident if the airbag inflates for
some reason.)

Store the steering wheel pad where the ambient temperature remains below 93

°

C (200

°

F), without

high humidity and away from electrical noise.

Be careful not to let painting materials contact the airbag sensors.

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

INTRODUCTION

IN-7

Shift Lock ECU

Tilt and Power
Telescopic ECU

Airbag ECU

Cruise Control ECU

Engine ECU

ABS and Traction ECU
(w/ Traction System) or
ABS ECU
(w/o Traction System)

Theft Deterrent and
Door Lock ECU

(w/ Traction System)

Traction ECU

Remote Control Mirror ECU

A/C Control Amplifier

PPS ECU

Engine Cooling Fan ECU

Component to be aligned

Section of repair manual 

for relevant model year

Front Wheels

Suspension and Axle (SA) section

Rear Wheels

Suspension and Axle (SA) section

Propeller Shaft

Propeller Shaft (PR) section

2. BRAKE SYSTEM

The brake system is one of the most important safety components. Always follow the directions and
notes given in section BR of the repair manual for the relevant model year when handling brake sys-
tem parts.
NOTICE: When repairing the brake master cylinder or TRAC system, bleed the air out of the TRAC
system.

3. DRIVE TRAIN AND CHASSIS

The drive train and chassis are components that can have great effects on the running performance
and vibration resistance of the vehicle. After installing components in the sections listed in the table
below, perform alignments to ensure correct mounting angles and dimensions. Particularly accurate
repair of the body must also be done to ensure correct alignment.
HINT: Correct procedures and special tools are required for alignment. Always follow the directions
given in the repair manual for the relevant model year during alignment and section DI of this manual.

4. ECU (ELECTRONIC CONTROL UNIT)

Locations of ECUs

INTRODUCTION

IN-8