1991 LEXUS SC400 steering wheel

INSPECTION PROCEDURE
When storing steering wheel pad, keep upper
surface of pad facing upward.
Preparation.
(1) Disconnect battery negative (±) terminal cable, and wait at least 20 seconds.
(2) Remove steering wheel pad (See page AB±14).
Disconnect center airbag sensor assembly connector.
Check front airbag sensor circuit (Measure resistance between terminals +SR
and ±SL and ±SL of center airbag sensor assembly connector.).
Measure resistance between terminals +SR and ±SR,
+SL and ±SL of harness side connector of center air-
bag sensor assembly.
Resistance: 755
± 885

Go to step
AB±70±
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3
Codes other than code 15 may be output at this
time, but this is not relevant to this check.Replace front airbag sensor.
NG
OK
(1) Turn ignition switch ACC or ON, and wait at least 20
seconds.
(2) Using SST, connect terminals Tc and E
1 of TDCL.
SST 09843±18020
(3) Check diagnostic code.
Check center airbag sensor assmbly.
Check front airbag sensor.
Replace center airbag sensor assembly.NG
OK
Diagnostic code 15 is not output.
(1) Connect connector to center airbag sensor
assembly.
(2) Using a service wire, connect D+ and D± on spiral cable side of connector between spiral
cable and steering wheel pad.
(3) Connect negative (±) terminal cable to battery, and wait at least 2 seconds.
From the results of the above inspection, the malfunctioning part can no\
w be considered normal.
To make sure of this, use the simulation method to check.
4
Disconnect front airbag sensor connector. Measure resistance between each terminal of
front airbag sensor.

Do not touch ohmmeter probes strongly
against terminals of front airbag sensor.

Make sure the front airbag sensor connector
is properly connected.
Terminal Resistance
Below 1 
755
 ±885 
1 M or higher
+S ± +A
+S ± ±S
±S ± ±A
±
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Check ECU±B fuse.
NG
OK
1
6Go to step
(1) Disconnect battery negative (±) terminal cable, and wait at least 20 seconds.
(2) Remove steering wheel pad (See page AB±14).
When storing steering wheel pad, keep upper
surface of pad facing upward.
NG
OKRepair.
Check connection of center airbag sensor assembly connector.2
3Preparation.
INSPECTION PROCEDURE
HINT: If airbag warning light does not light up, perform the following troubl\
eshooting:
±
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DISPOSAL OF STEERING WHEEL
PAD (WITH AIRBAG)
When scrapping vehicles equipped with an airbag system or dis-
posing of a steering wheel pad (with airbag), always first deploy
the airbag in accordance with the procedure described below.
If any abnormality occurs with the airbag deployment, contact the
SERVICE DEPT. of TOYOTA MOTOR SALES, U.S.A., INC..
Never dispose of a steering wheel pad which has an
undeployed airbag.
When disposing of a steering wheel pad with an airbag deployed
in a collision, follow the same procedure given under ªAIRBAG
DEPLOYMENT PROCEDURE (WHEN SCRAPPING THE VE-
HICLE), part 5, DISPOSAL OF STEERING WHEEL PAD (WITH
AIRBAG)º (See page AB±93).
PRECAUTIONS FOR AIRBAG DEPLOYMENT
1. The airbag produces a sizeable exploding sound when
it deploys, so perform the operation out±of±doors and
where it will not create a nuisance to nearby residents.
2. When deploying the airbag, always use the specified
SST; SRS AIRBAG DEPLOYMENT TOOL (SST
09082±00700). Perform the operation in a place away
from electrical noise.
3. When deploying an airbag, perform the operation from at least 10 m (33 ft) away from the steering wheel pad.
4. The steering wheel pad is very hot when the airbag is deployed, so leave it alone for at least 30 minutes after
deployment.
5. Use gloves and safety glasses when handling a steering
wheel pad with deployed airbag.
6. Always wash your hands with water after completing the operation.
7. Do not apply water, etc. to a steering wheel pad with deployed airbag.
AIRBAG DEPLOYMENT PROCEDURE
(WHEN SCRAPPING VEHICLE)
HINT: Have a battery ready as the power source to deploy the
airbag.
1. DISCONNECT NEGATIVE (±) TERMINAL CABLE FROM BATTERY
CAUTION: Work must be started after approx. 30 sec-
onds or lo nger from the time the ignition switch is turned
to the LOCK position and the negative (±) terminal cable
is disconnected from the battery (See page AB±2).
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SRS AIRBAG Disposal of Steering Wheel Pad (with Airbag)AB±91
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2. CONFIRM FUNCTIONING OF SST (See page AB±97)
SST 09082±00700
3. INSTALL SST CAUTION: Check that there is no looseness in the
steering wheel and steering wheel pad.
(a) Remove the No. 1 under cover.
(b) Disconnect the airbag connector of the spiral cable.
(c) Connect the SST connector to the airbag connector ofthe spiral cable.
SST 09082±00700
(d) Move the SST to at least 10 m (33 ft) from the front of the
vehicle.
(e) Close all the doors and windows of the vehicle.
NOTICE: Take care not to damage the SST wire harness.
(f) Connect the SST red clip to the battery positive (+) terminal and the black clip to the battery negative (±)
terminal.
4. DEPLOY AIRBAG (a) Confirm that no±one is inside the vehicle or within 10 (33 ft) of the vehicle.
(b) Press the SST activation switch and deploy the airbag.
HINT: The airbag deploys simultaneously as the LED of the
SST activation switch lights up.
AB±92
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5. DISPOSAL OF STEERING WHEEL PAD (WITH AIRBAG)CAUTION:
w The steering wheel pad is very hot when the airbag is
deployed, so leave it alone for at least 30 minutes after
deployment.
w Use gloves and safety glasses when handling a steering
wheel pad with deployed airbag.
w Do not apply water, etc. to a steering wheel pad with
deployed airbag.
w Always wash your hands with water after completing the
operation.
(a) When scrapping a vehicle, deploy the airbag and scrap
the vehicle with the steering wheel pad still installed.
(b) When moving a vehicle for scr apping which has a
steering wheel pad with deployed airbag, use gloves
and safety glasses.
AIRBAG DEPLOYMENT PROCEDURE
(PROCEDURE FOR DISPOSAL OF
STEERING WHEEL PAD ONLY)
When disposing of the steering wheel pad (with airbag)
only, never use the customer's vehicle to deploy the
airbag.
Remove the steering wheel pad from the vehicle and be sure
to follow the procedure given below when deploying the
airbag.
HINT: Have a battery ready as the power source to deploy the
airbag.
1. REMOVE STEERING WHEEL PAD (SEE PAGE AB±16)
CAUTION:
wWhen removing the steering wheel pad (with
airbag), work must be started after approx. 30
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.
w When storing the steering wheel pad, keep the upper
surface of the pad facing upward.
2. REMOVE STEERING WHEEL PAD CONNECTOR
Remove the connector on the steering wheel pad rear
surface from the inflater cover.
±
SRS AIRBAG Disposal of Steering Wheel Pad (with Aribag)AB±93
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3.14 X (Diameter)2
4
3. FIX STEERING WHEEL PAD TO DISC WHEEL WITH TIRE(a) Install bolts with washers in the four bolt holes in thesteering wheel pad.
Bolt: L 35.0 mm (1.4 in.) M 6.0 mm
Pitch 1.0 mm
NOTICE: Tighten the bolts by hand until the bolts
become difficult to turn.
Do not tighten the bolts too much.
(b) Using a service±purpose wire harness for vehicle, tie down the steering wheel pad to the disc wheel.
Wire harness: Stripped wire harness section 1.25 mm or
more (0.002 in. or more)
HINT: To calculate the square of the stripped wire harness
section ±
Square =
CAUTION: If a wire harness which is too thin or some oth-
er thing is used to tie down the steering wheel pad, it may
be snapped by the shock when the airbag is deployed,
this is highly dangerous. Always use a wire harness for
vehicle use which is at least 1.25 mm (0.002 in.).
(c) Using 3 wire harnesses, wrap the wire harnesses at least 2 times each around the bolts installed on the left
and right sides of the steering wheel pad.
CAUTION: Tightly wind the wire harness around the bolts
so that there is no slack.
If there is slackness in the wire harness, the steering
wheel pad may come loose due to the shock when the
airbag is deployed, this is highly dangerous.
(d) Face the upper surface of the steering wheel pad upward. Separately tie the left and right sides of the steering
wheel pad to the disc wheel through the hub nut holes.
Position the steering wheel pad connector so that it
hangs downward through a hub hole in the disc wheel.
CAUTION:
wMake sure that the wire harness is tight. It is very
dangerous if looseness in the wire harness results
in the steering wheel pad coming free through the
shock of the airbag deploying.
AB±94
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wAlways tie down the steering wheel pad with the pad
side facing upward. It is very dangerous if the steer-
ing wheel pad is tied down with the metal surface
facing upward as the wire harness will be cut by the
shock of the airbag deploying and the steering
wheel pad will be thrown into the air.
HINT:
w The disc wheel will be marked by airbag deployment, so
use a redundant disc wheel.
4. CONFIRM FUNCTIONING OF SST (SEE PAGE AB±94)
SST 09082±0700
5. INSTALL SST CAUTION: Place the disc wheel on level ground.
(a) Connect the SST connector to the steering wheel pad
connector.
SST 09082±00700
NOTICE: To avoid damaging the SST connector and wire
harness, do not lock the secondary lock of the twin lock.
Also, provide some slack for the SST wire harness inside
the disc wheel.
(b) Move the SST to at least 10 m (33 ft) away from the steering wheel pad tied down on the disc wheel.
6. COVER STEERING WHEEL PAD WITH CARDBOARD BOX OR TIRES
(Covering Method Using Cardboard Box)
Cover the steering wheel pad with the cardboard box and
weigh the cardboard box down in four places with a at least
20 kg (44 lb, 196 N).
Size of cardboard box: Must exceed the following dimen-
sions ±x = 460 mm (18.11 in.)
When dimension y of the cardboard box exceeds
the diameter of the disc wheel with tire the steering
wheel pad is tied to±
x = 460 mm (18.11 in.) + width of tire
y = 650 mm (25.59 in.)
NOTICE: If a cardboard box smaller than the size speci-
fied is used, the cardboard box will be broken by the
shock of the airbag deployment.
±
SRS AIRBAG Disposal of Steering Wheel Pad (with Aribag)AB±95
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