1991 LEXUS SC400 steering

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 90 seconds from
the time the ignition switch is turned to the LOCK posi-
tion and the negative (±) terminal cable is disconnected
from the battery (See page RS±2).
2. CONFIRM FUNCTIONING OF SST (See page RS±27)
SST 09082±00700
3. INSTALL SST CAUTION: Check that there is no looseness in the steer-
ing 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 of the 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.
RS±22±
SUPPLEMENTAL RESTRAINT SYSTEM STEERING WHEEL PAD AND SPIRAL CABLE
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4. DEPLOY AIRBAG
(a) Confirm that no±one is inside the vehicle or within 10 m (33ft) 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.
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 scrapping which has a steering
wheel pad with deployed airbag, use gloves and safety
glasses.
When disposing of the steering wheel
pad only
When disposing of the steering wheel pad (with airbag)
only, never use the customer's vehicle to deploy the air-
bag.
Remove the steering wheel pad from the vehicle and be sure
to follow the procedure given below when deploying the air-
bag.
HINT: Have a battery ready as the power source deploy the
airbag.
1. REMOVE STEERING WHEEL PAD (See page RS±18)
CAUTION:
w When removing the steering wheel pad (with airbag),
work must be started after 90 seconds 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.
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SUPPLEMENTAL RESTRAINT SYSTEM STEERING WHEEL PAD AND SPIRAL CABLERS±23
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2. REMOVE STEERING WHEEL PAD CONNECTORRemove the connector on the steering wheel pad rear sur-
face from the inflater cover.
3. FIX STEERING WHEEL PAD TO DISC WHEEL WITH TIRE
(a) Install the 4 bolts with washer in the 4 bolt holes in the steering wheel pad.
Bolt:
L 35.0 mm (1.398 in.) M 6.0 mm (0.236 in.) Pitch 1.0 mm
(0.039 in.)
NOTICE:
wTighten the bolts by hand until the bolts become difficult
to turn.
w 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
2 or more (0.0019 in2 or more)
HINT: To calculate the square of the stripped wire harness
section ±±
Square = 3.14 x (Diameter)2 divided by 4
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 chock when the airbag is deployed,
this is highly dangerous. Always use a wire harness for
vehicle use which is at least 1.25 mm
2 (0.0019 in2.).
(1) 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:
w Tightly wind the wire harness around the bolts so that
there is no slack.
w 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.
RS±24±
SUPPLEMENTAL RESTRAINT SYSTEM STEERING WHEEL PAD AND SPIRAL CABLE
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(2) Face the upper surface of the steering wheel pad upward.
(3) Separately tie the left and right sides of the steering wheelpad to the disc wheel through the hub nut holes.
(c) Position the steering wheel pad connector so that it hangs downward through a hub hole in the disc wheel.
CAUTION:
w Make 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.
w Always tie down the steering wheel pad with the pad side
facing upward. It is very dangerous if the steering 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: The disc wheel will be marked by airbag deployment,
so use a redundant disc wheel.
4. CONFIRM FUNCTIONING OF SST (See page RS±27)
SST 09082±00070
5. INSTALL SST CAUTION: Place the disc wheel on level ground.
(a) C onnect 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.
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SUPPLEMENTAL RESTRAINT SYSTEM STEERING WHEEL PAD AND SPIRAL CABLERS±25
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6. COVER STEERING WHEEL PAD WITH CARDBOARDBOX 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
196 N (20 kgf, 44 lbf).
Size of cardboard box:
Must exceed the following dimensions±
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.
Covering Method Using Tires:
Place at least 3 tires without disc wheel on top of the disc
wheel with tire to which the steering wheel pad is tied.
Tire size: Must exceed the following dimensions± Width 185 mm (7.28 in.)
Inner diam 360 mm (14.17 in.)
CAUTION: Do not use tires with disc wheels.
NOTICE: The tires by marked by the airbag deployment,
so use redundant tires.
7. AIRBAG DEPLOYMENT
(a) Connect the SST red clip to the battery positive (+) terminal and the black clip to the battery negative (±) terminal.
(b) Confirm that no±one is within 10 m (33 ft) of the disc wheel the steering wheel pad is tied to.
(c) Press the SST activation switch and deploy the airbag. HINT: The airbag deploys simultaneously as the LED of the
SST activation switch lights up.
RS±26±
SUPPLEMENTAL RESTRAINT SYSTEM STEERING WHEEL PAD AND SPIRAL CABLE
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8. DISPOSAL OF STEERING WHEEL PAD (WITH AIRBAG)CAUTION:
w The steering wheel pad is battery 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) Remove the steering wheel pad from the disc wheel.
(b) Place the steering wheel pad in a vinyl bag, tie the end tightly
and dispose of it the same way as other general parts.
CONFIRM FUNCTIONING OF SST
RS014±02
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 supplemental restraint 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.
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SUPPLEMENTAL RESTRAINT SYSTEM STEERING WHEEL PAD AND SPIRAL CABLERS±27
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DTC11Short in Squib Circuit or Front Airbag Sen-
sor Circuit (to Ground)
CIRCUIT DESCRIPTION
The squib circuit consists of the center airbag sensor assembly, spiral cable and the steering wheel pad (squib),
wire harness connector and front passenger airbag assembly (squib). It\
causes the SRS to operate when the
SRS operation conditions are satisfied.
The front airbag sensor detects the deceleration force in a frontal collisi\
on and is located in the front fender on
the left and right sides.
For details of the function of each component, see FUNCTION OF COMPONENTS o\
n page RS±10. Diagnostic
trouble code 11 is recorded when occurrence of ground short is detected in the squib ci\
rcuit or front airbag sen-
sor circuit.
DTC No.Diagnosis
11
 Short circuit in squib wire harness (to ground)
 Squib malfunction
 Short circuit in front airbag sensor +S, D
+, D±, P+, P± wire harness (to ground).
 Front airbag sensor malfunctions.
 Short circuit between +S wire harness and ±S wire harness of front ai\
rbag sensor.
 Spiral cable malfunction.
 Center airbag sensor assembly malfunction.
RS±70±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTING
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OKNG
INSPECTION PROCEDURE
1Preparation.
P1. Disconnect battery negative (±) terminal cable, andwait at least 90 seconds.
2. Remove steering wheel pad (See page RS±19).
3. Disconnect connectors of front passenger airbag assembly (See page RS±32).
Caution: Store the steering wheel pad with the
surface facing upward.
2Check front airbag sensor circuit. (Measure resistance between terminals +SR and ±SR, +SL
and ±SL of center airbag sensor assembly connector.)
C
OK
PDisconnect center airbag sensor assembly connector.
Measure resistance between terminals +SR and ±SR,
+SL and ±SL of harness side connector o center airbag
sensor assembly.
Resistance: 755
± 885

Go to step

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SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±73
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