light LEXUS SC400 1991 Service Repair Manual

GEAR HOUSING
If the gear housing is secured directly in a vise during overhaul, there i\
s danger of deforming it, so always
first secure it in the SST provided (rack & pinion steering rack housing stand) before placing it in the vise.
The oil seals on both sides of the power cylinder are for the prevention of\
leakage of the high pressure fluid
which acts on the piston. Always use new oil seals when reassembling and be v\
ery careful not to scratch
or damage them.
Because of the high pressure, even the slightest scratch will cause fluid leakage, \
resulting in an inoperative
power steering system.
Also, be very careful not to scratch the sliding portion of the rack which ma\
kes contact with the oil seals.
When removing the rack ends from the rack, it is very easy to cause a burr w\
hen holding the tip of the rack
with a wrench. Therefore, before assembling the rack, first check the tip fo\
r burrs and remove any with an
oil stone.
Teflon rings are used for the piston and control valve. These teflon rings are highly durable against wear,
but if it is necessary to replace them, be careful not to stretch the new o\
nes.
After installing a teflon ring into its groove, snug it down into the gr\
oove before assembly of the cylinder
or housing to prevent possible damage.
SR±106
±
STEERING POWER STEERING
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POWER STEERING PUMP
DISASSEMBLY
SR0G7±02
1. MOUNT POWER STEERING PUMP IN VISE
NOTICE: Do not tighten the vise too tight.
2. REMOVE PUMP PULLEY
(a) Using SST, remove the pulley set nut.SST 09278±54012
(b) Remove the pulley.
3. REMOVE SUCTION PORT UNION
(a) Remove the 2 bolts and union.
(b) Remove the O±ring from the union.
4. REMOVE PRESSURE PORT UNION, FLOW CONTROL
VALVE AND SPRING
(a) Remove the pressure port union.
(b) Remove the O±ring from the union.
(c) Remove the flow control valve and spring.
5. REMOVE SPRING SEAT
(a) Using snap ring pliers, remove the snap ring. HINT: The snap ring is easier to remove if the spring seat is
pressed down slightly.
(b) Temporarily install a bolt to the seat and pull out it. HINT: Use a bolt with diameter 6 mm (0.24 in.) and pitch 1.0
mm (0.039 in.).
(c) Remove the O±ring from the seat.
±
STEERING POWER STEERINGSR±121
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(b) Using SST, press the rack until the end stopper slightlytouches the press block.
SST 09612±24014 (09612±10061)
(c) Slightly tap the rack end with a brass bar and hammer.
(d) Pull out the rack with cylinder end stopper, 2 spacers and oil seal.
16. REMOVE RACK HOUSING OIL SEAL AND SPACER Using SST, tap out the oil seal and spacer.
SST 09631±12020, 09631±20031
GEAR HOUSING COMPONENTS
INSPECTION AND REPAIR
SR0NZ±01
1. INSPECT RACK
(a) Using a dial indicator, check the rack for runout and for teethwear or damage.
Maximum runout:
0.3 mm (0.012 in.)
(b) Check the back surface for wear or damage.If faulty, replace it.
2. IF NECESSARY, REPLACE RACK HOUSING BEARING AND OIL SEAL
(a) Using SST, remove the bearing. SST 09612±30012
NOTICE: Be careful not to damage the rack housing.
±
STEERING POWER STEERINGSR±153
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ON±VEHICLE INSPECTION
SR0E9±02
CHECK THAT STEERING WHEEL FREEPLAY IS COR-
RECT
With the vehicle stopped and tires pointed straight ahead,
rock the steering wheel gently back and forth with light finger
pressure.
Freeplay should not exceed the maximum.
Maximum freeplay:30 mm (1.18 in.)
If incorrect, repair.
±
STEERING ON±VEHICLE INSPECTIONSR±3
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9. SELECT 2 PAWL STOPPERS
(a) With the tilt pawl and ratchet engaged, install the 2 pawlstoppers.
(b) Check that the alignment marks on the stopper and pawl
align when the stopper is lightly rotated to the pawl side.
(c) If the alignment marks do not align, select pawl stoppers according to the following table.
 

Tilt lever side
 

Tilt sub lever side
 

Dimension ªAº
mm (in.)
 

1
 

A
 

12.68 ± 12.74
(0.4992 ± 0.5016)
 

2
 

B
 

12.61±12.67
(0.4965 ± 0.4988)
 

3
 

C
 

12.54 ± 12.60
(0.4937 ± 0.4961)
 

4
 

D
 

12.47 ± 12.53
(0.4909± 0.4933)
 

5
 

E
 

12.40 ± 12.46
(0.4882 ± 0.4906)
 

6
 

F
 

12.33 ± 12.39
(0.4854 ± 0.4878)
 

7
 

G
 

12.26 ± 12.32
(0.4827 ± 0.4850)
(d) After selecting the stoppers, check that on both sides the
pawl and ratchet are fully engaged.
10. I N S TA L L 2 PAW L S TO PPERS AND 2 TILT LEVER
RETAINERS
(a) Install the tilt sub lever side pawl stopper and retainer.
(b) Install the spacer and new E±ring.
(c) Install the nut to the tilt steering bolt.
Torque: 15 N Vm (150 kgf Vcm, 11 ft Vlbf)
(d) Install the collar to the tilt memory bolt.
(e) Install the nut to the tilt memory bolt.
Torque: 5.9 N Vm (60 kgf Vcm, 52 in. Vlbf)
(f) Install the tilt lever side pawl stopper and tilt lever retainer.
(g) Install the E±ring.
(h) Install and torque the nut.
Torque: 15 N Vm (150 kgf Vcm, 11 ft Vlbf)
SR±22±
STEERING STEERING COLUMN
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WIRING DIAGRAM
SRS Warning Light System (Always Lit Up, when ignition switch in
LOCK position)
CIRCUIT DESCRIPTION
The SRS warning light is located on the combination meter.
When the supplemental restraint system is normal, the SRS warning light ligh\
ts up for approx. 6 seconds after
the ignition switch is turned from LOCK position to ACC or ON position, and\
then turns off automatically.
If there is a malfunction in the supplemental restraint system, the SRS wa\
rning light lights up to inform the driver
of the abnormality.
When terminals Tc and E
1 of the DLC2 are connected, the diagnostic trouble code is displayed by \
the blinking
of the SRS warning light.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
HINT: If the SRS warning light is always lit up by a DTC check procedure, per\
form Tc T erminal circuit check proce-
dure (See page RS±121).
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±119
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YESNO
INSPECTION PROCEDURE
1Does SRS warning light turn off?
C
Hint
P1. Turn ignition switch LOCK.
2. Disconnect negative (±) terminal cable from battery
and wait at least 90 seconds.
3. Remove steering wheel pad (See page RS±19).
4. Disconnect connectors of front passenger airbag assembly (See page RS±32).
5. Disconnect center airbag sensor assembly con- nector.
6. Connect negative (±) terminal cable to battery.
Check operation of SRS warning light.
Ignition Switch is LOCK position.
Check SRS warning light circuit or terminal AB circuit of
DCL1 or DLC2.
Replace center airbag sensor assembly.
RS±120±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTING
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Tc Terminal Circuit
CIRCUIT DESCRIPTION
By connecting terminal Tc and E1 of the DLC1 or DLC2, the center airbag sensor assembly is set in the di\
agnos-
tic trouble code output mode. The diagnostic trouble codes are displayed\
by the blinking of the SRS warning
light.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
Troubleshooting for this system is different depending on whether the diagnostic trouble code is not displayed\
SRS warning light is always lit up with a DTC check procedure, or is displa\
yed without a DTC check procedure.
Confirm the problem symptoms first before selecting the appropriate troubleshoo\
ting procedure.
HINT: If the diagnostic trouble code is not displayed or SRS warning light is\
always lit up with a DTC check proce-
dure perform the following troubleshooting:
±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTINGRS±121
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NGOK
3Check center airbag sensor assembly.
C
OK
P1. Turn ignition switch LOCK.
2. Disconnect battery negative (±) terminal cable, andwait at least 90 seconds.
3. Remove steering wheel pad (See page RS±19).
4. Disconnect connectors of front passenger airbag assembly (See page RS±32).
Check operation of SRS warning light.
SRS warning light comes on.
Check harness between center airbag sensor assembly
and DLC1 or DLC2.
Replace center airbag sensor assembly.
RS±124±
SUPPLEMENTAL RESTRAINT SYSTEM TROUBLESHOOTING
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GENERAL DESCRIPTION
The LEXUS SC400/300 is equipped with an SRS (Supplemental Restraint System\
) such as the driver
airbag and front passenger airbag. Failure to carry out service operations in \
the correct sequence
could cause the SRS to unexpectedly deployed during servicing, possibly leadin\
g to a serious acci-
dent. Further, if a mistake is made in servicing the supplemental restraint system, i\
t is possible the
SRS may fail to operate when required. Before performing servicing (inc\
luding removal or installa-
tion of parts, inspection or replacement), be sure to read the followin\
g items carefully, then follow
the correct procedure described in the repair manual.
1. Malfunction symptoms of the supplemental restraint system are difficult to confirm, so the diagnostic trouble codes become the most important source of information when troubleshooting. When
troubleshooting the supplemental restraint system, always inspect the diagnostic trouble codes before
disconnecting the battery (See page RS±59).
2. Work must be started after 90 seconds from the time the ignition switch turn\
ed to the LOCK position
and the negative (±) terminal cable is disconnected from the battery. (The supplemental restraint
system is equipped with a back±up power source so that if work is sta\
rted within 90 seconds of
disconnecting the negative (±) terminal cable of the battery, the SRS may be deployed.)
When the negative (±) terminal cable is disconnected from the battery, memory of the clock and audio sys-
tems will be canceled. So before starting work, make a record of the contents memo\
rized by the audio
memory system. When work is finished, reset the audio systems as before and ad\
just 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 custom-
er, 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 SRS does not deploy, the steering wheel pad, front passenger
airbag assembly, front airbag sensors and center airbag sensor assembly should be inspe\
cted (See pages
RS±16 , 28 , 41 and 44).
4. Never use SRS parts from another vehicle. When replacing parts, replace \
them with new parts.
5. Before repairs, remove the airbag sensor if shocks are likely to be applied to the sensors during r\
epairs.
6. Never disassemble and repair the steering wheel pad, front passenger airbag a\
ssembly, front airbag sensors or center airbag sensor assembly in order to reuse it.
7. If the steering wheel pad, front passenger airbag assembly, front airbag sensors or center airbag sensor assembly have been dropped, or if there are cracks, dents or dents or ot\
her defects in the case, bracket
or connector, replace them with new ones.
8. Do not expose the steering wheel pad, front passenger airbag assembly, front airbag sensors and center airbag sensor assembly directly to hot air or flames.
9. Use a volt/ohmmeter with high impedance (10 k
/V minimum) of troubleshooting of the system's electrical
circuit.
10. Information labels are attached to the periphery of the SRS components. \
Follow the instructions on the
notices.
11. After work on the supplemental restraint system is completed, perform the SRS\
warning light check (See page RS±59 ).
12. If the vehicle is equipped with a mobile communication system, refer to \
the precaution in the IN section. RS±2
±
SUPPLEMENTAL RESTRAINT SYSTEM GENERAL DESCRIPTION
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