1991 LEXUS SC400 steering wheel

INSPECTION ITEMS AND REPLACEMENT REQUIREMENTS
If a Vehicle is brought in for an airbag system inspection, or if a vehicle wh\
ich has been involved in a collision
is inspected, perform the inspection in accordance with the following proc\
edure. If any problems are discovered,
replace the affected part with a new one.
Steering Wheel Pad (with Airbag), Steering Wheel and Spiral
Cable
INSPECTION ITEMS
1. VEHICLES NOT INVOLVED IN A COLLISION(a) Perform a diagnostic system check (See page AB±30).
(b) Perform a visual check which includes the following items with the steering wheel pad (with airbag) installed in the vehicle.
w Check for cuts, minute cracks or marked discoloration of
the steering wheel pad top surface and grooved portion.
2. VEHICLES INVOLVED IN A COLLISION IF THE AIRBAG IS NOT DEPLOYED
(a) Perform a diagnostic system check (See page AB±30).
(b) Perform a visual check which includes the following items with the steering wheel pad (with airbag) removed from the vehicle.
w Check for cuts or cracks in, or marked discoloration of the
steering wheel pad top surface and grooved portion.
w Check for cuts and cracks in, or chipping of connectors and
wire harnesses.
w Check for deformation of the horn button contact plate of
the steering wheel.
HINT: w If the horn button contact plate of the steering wheel is
deformed, never repair it. Always replace the steering
wheel assembly with a new one.
w There should be no interference between the steering
wheel pad and the steering wheel, and the clearance
should be uniform all the way around when the new
steering wheel pad is installed on the steering wheel.
CAUTION: For removal and installation of the steering wheel
pad, see page AB±14, ªREMOVAL AND INSTALLATIONº and be
sure to follow the correct procedure.
IF THE AIRBAG IS DEPLOYED
(a) Perform a diagnostic system check (See page AB±30).
(b) Perform a visual check which includes the following items with the steering wheel pad (with airbag) removed from the vehicle.
w Check for deformation of the horn button contact plate of
the steering wheel.
w Check for damage to the spiral cable connector and wire
harness.
AB±9SRS AIRBAG ± Inspection Items and Replacement Requirements
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HINT:
w If the horn button contact plate of the steering wheel is deformed, never \
repair it. Always replace the
steering wheel assembly with a new one.
w There should be no interference between the steering wheel pad and the steeri\
ng wheel, and the
clearance should be uniform all the way around when the new steering wheel pad is\
installed on the
steering wheel.
REPLACEMENT REQUIREMENTS
In the following cases, replace the steering wheel pad, steering wheel or \
spiral cable.
CAUTION: For replacement of the steering wheel pad, see page AB±16, ªREMOVAL AND INSTALLA-
TIONº and be sure to follow the correct procedure.
w If the airbag has been deployed.
w If the steering wheel pad or spiral cable has been found to be faulty in\
troubleshooting.
w If the steering wheel pad, steering wheel or spiral cable has been found t\
o be faulty during the check
in item 1±(b) or 2±(b).
w If the steering wheel pad has been dropped.
Front Airbag Sensor
INSPECTION ITEMS
1. VEHICLES NOT INVOLVED IN A COLLISION
w Perform a diagnostic system check (See page AB±30).
2. VEHICLES INVOLVED IN A COLLISION (a) Perform a diagnostic system check (See page AB±30).
(b) If the front fender of the car or its periphery is damaged, perform visual check for damage to the front airbag
sensor, which includes the following items even if the
airbag was not deployed:
w Bracket deformation.
w Peeling of paint from the bracket.
w Cracks, dents or chips in the case.
w Cracks and dents in, or chipping and scratches of
the connector.
w Peeling off of the label or damage to the series
number.
Also refer to the body dimension drawings on page
BO±133 and check the dimensions and mounting sur-
face angle of the body area where the front airbag sen-
sors are mounted.
AB±10SRS AIRBAG ± Inspection Items and Replacement Requirements
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PREPARATION
SST (SPECIAL SERVICE TOOLS)
09082±00700SRS Airbag
Deployment Tool
09213±31021Crankshaft Pulley
Puller
09843±18020Diagnosis Check
Wiring
Steering wheel
RECOMMENDED TOOLS
09042±00010Torx Socket
T30
09042±00020Torx Socket
T30
09082±00015TOYOTA
Electrical Tester
Center airbag sensor assembly
Steering wheel pad
EQUIPMENT
Part NameNote
Torque wrench
AB±13SRS AIRBAG ± Preparation
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REMOVAL AND INSTALLATION OF
COMPONENT PARTS
Steering Wheel Pad and Spiral Cable
Removal and install the parts as shown.
(MAIN POINTS OF REMOVAL AND
INSTALLATION)
CAUTION: Work must be started after approx. 20 se-
conds or longer 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).
NOTICE:
wIf the wiring connector of the airbag system is discon-
nected with the ignition switch at ON or ACC, diagnostic
codes will be recorded.
wNever use airbag parts from another vehicle. When re-
placing parts, replace with new parts.
1. REMOVE STEERING WHEEL PAD (a) Remove negative terminal (±) from the battery.
(b) Place the front wheels facing straight ahead.
(c) Using a torx wrench, loosen the four screws.
Torx wrench: T30 (Part No. 09042±00010 or locally manufac-
tured tool)
(d) Loosen the torx screws until the groove along the screwcircumference catches on the screw case.
AB±14
SRS AIRBAG
± Removal and Installation of Component Parts
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(e) Pull the wheel pad out from the steering wheel anddisconnect the airbag connector.
NOTICE: When removing the wheel pad, take care not to
pull the airbag wire harness.
CAUTION:
wWhen storing the wheel pad, keep the upper surface of
the pad facing upward (See pages AB±3, 4).
wNever disassemble the wheel pad.
2. REMOVE STEERING WHEEL
(a) Disconnect the connector.
(b) Remove the set nut.
(c) Place matchmarks on the steering wheel and mainshaft.
(d) Using SST, remove the steering wheel.
SST 09213±31021
3. REMOVE AND INSTALL SPIRAL CABLE FROM/TO COMBINATION SWITCH (See page BE±41)
NOTICE: Do not disassemble the spiral cable or apply oil
to it.
4. CENTER SPIRAL CABLE (a) Check that the front wheels are facing straight ahead.
(b) Turn the spiral cable counterclockwise by hand until it
becomes harder to turn the cable.
(c) Then rotate the spiral cable clockwise about 3 turns to align the red mark.
HINT: The spiral cable will rotate about 3 turns to either left
or right of the center.
5. INSTALL STEERING WHEEL (a) Align matchmarks on the steering wheel and main shaft,
and install the steering wheel to the main shaft.
(b) Install and torque the set nut.
Torque: 35 N Vm (360 kgf Vcm, 26 ft Vlbf)
(c) Connect the connector.
6. INSTALL STEERING WHEEL PAD (a) Connect the airbag connector.
(b) I n s t a l l t h e w heel pad after confirming that the
circumference groove of the torx screws is caught on the
screw case.
(c) Using a torx wrench, tighten the four screws.
Torque: 7.4 N Vm (75 kgf Vcm, 65 in. Vlbf)
NOTICE:
wMake sure the wheel pad is installed to the specified
torque.
wIf the wheel pad has been dropped, or there are cracks,
dents or other defects in the case or connector, replace
the wheel pad with a new one.
wWhen installing the wheel pad, take care that the wirings
do not interfere with other parts and are not pinched
between other parts.
7. CHECK STEERING WHEEL CENTER POINT AB±15
SRS AIRBAG
± Removal and Installation of Component Parts
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Description
The SRS (Supplemental Restraint System) airbag, together with
the seat belt, is designed to help protect the driver. In a collision,
the airbag sensors detect the shock, and if the front±to±rear shock
is greater than a specified value, an airbag stored in the steering
wheel pad is inflated instantaneously to help reduce the shock to
the driver.
LOCATION OF COMPONENTS
AB±24SRS AIRBAG ± Troubleshooting
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NOTICE: When connecting the battery after clearing the malfunction code, always\
do it with the igni-
tion switch in LOCK position. When the battery has been reconnected, turn the ignition switch to
ACC or ON position after at least 2 seconds have elapsed.
If the battery is reconnected with the ignition switch in ACC or ON posi\
tion, or the ignition switch
is turned to ACC or ON within 2 seconds of connecting the battery, it is possible that the diagnosis
system will not operate normally.
HINT: Determine the malfunction in the airbag system in step [ 6 ] by whethe\
r or not a malfunction code
other than code 41 is output.
7. DIAGNOSTIC CODE CHART Proceed to the appropriate flow chart in step [ 8 ] in accordance with the malfunction code found in step
[ 5 ] or [ 6 ].
8. CIRCUIT INSPECTION [ 9 ] REPAIR Find out if the problem lies in a sensor, actuator or wire harness and connector, and repair the problem.
After the problem part is repaired, reinstall the disassembled parts. Do not \
start work until at least 20 se-
conds after the ignition switch is turned to the LOCK position and the negati\
ve (±) terminal cable is discon-
nected.
CAUTION: If incorrect procedure is used, a malfunction may occur in the system o\
r there is the dan-
ger that airbag may be accidentally activated during the repair operation. Carefully read the GEN-
ERAL DESCRIPTION (See page AB±2) and the cautions for each operation, and perform repairs in
the correct order using the correct methods.
HINT: The following illustration for the CIRCUIT INSPECTION shows each conne\
ctor for the circuit from
the center airbag sensor assembly to the steering wheel pad (squib).
10 CLEARING OF MALFUNCTION CODE (EXCEPT CODE 41) When all the malfunction codes found in steps [ 5 ] and [ 6 ] have been repa\
ired, clear the malfunction
codes.
AB±26
SRS AIRBAG
± Troubleshooting
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DIAGNOSTIC CODES
CodeNo.Blink PatternDiagnosisTrouble AreaAIRBAG
Warning Light
(Nor

System normal±OFF
(Nor-
mal)
Source Voltage drop
Battery

Center airbag sensor assemblyON
11

Short in squib circuit
(to ground)

Front airbag sensor
malfunction

Flower sensor malfunction
Steering wheel pad (squib)

Front airbag sensor

Spiral cable

Center airbag sensor assembly

Wire harness
ON
12

Short in squib circuit
(to +B)
Steering wheel pad (squib)

Front airbag sensor

Spiral cable

Center airbag sensor assembly

Wire harness
ON
13

Short in squib circuit
(between D+ wire harness
and D± wire harness)

Steering wheel pad (squib)

Spiral cable

Center airbag sensor assembly

Wire harness
ON
14

Open in squib circuit
Steering wheel pad (squib)

Spiral cable

Center airbag sensor assembly

Wire harness
ON
15

Open in front airbag
sensor circuit
Front airbag sensor

Center airbag sensor assembly

Wire harness
ON
22

Airbag warning light
system malfunction
Airbag warning light

Center airbag sensor assembly

Wire harness
ON
31

Center airbag sensor
assembly malfunction

Center airbag sensor assemblyON
41

Malfunction stored in
memory

(Center airbag sensor assembly)ON
HINT:
w When the airbag warning light remains lit up and the diagnostic code in the n\
ormal code, this means a
source voltage drop.
This malfunction is not stored in memory by the center airbag sensor ass\
embly and if the power source
voltage returns to normal, after approx. 10 seconds the airbag warning l\
ight will automatically go out.
w Code 22 in recorded when a malfunction occurs in the airbag warning light sy\
stem. If an open malfunction
occurs in the airbag warning light system, the airbag warning light does not l\
ight up, so that until the
mal±function is repaired, the diagnostic codes (including code 22) cannot be confi\
rmed.
w When a malfunction occurs in the airbag system, malfunction codes 11 to 31 are output. After repairing
the malfunction indicated by malfunction codes 11 to 31, codes 11 to 31 are cleared from the memory, but
code 41 is output instead. Once the malfunction has been detected, the airba\
g warning light will remain
lit up until code 41 is cleared, even though the malfunction has been re\
paired.
w When 2 or more codes are indicated, the lowest numbered code will appear\
first.
w If a code not listed on the chart is displayed, then the center airbag s\
ensor assembly is faulty. AB±31
SRS AIRBAG
± Troubleshooting
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