battery replacement LEXUS SC300 1991 Service User Guide

REPLACEMENT OF RELAY BLOCK NO. 2
(B) IN RELAY BLOCK NO. 2
1. REMOVE RELAY BLOCK NO. 2 (B)
(a) Disconnect the battery terminals.CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and negative (±) terminal
cable is disconnected from the battery.
(b) Remove the relay block No. 2 cover.
(c) Remove the relay block No. 2 lower cover.
2. INSTALL RELAY BLOCK NO. 2 (B) For installation follow the removal procedure in reverse.
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BODY ELECTRICAL SYSTEM Power SourceBE±17
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Parts Replacement ± Headlight
(Headlight)
REPLACEMENT OF HEADLIGHT
1. REMOVE HEADLIGHT(a) Remove battery (LH) or disconnect negative termial (±)from the battery (RH).
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and negative (±) terminal
cable is disconnected from the battery.
(b) Remove fender liner. ( BO±92)
(c) Remove a screw and two nuts.
(d) Disconnect connector.
(e) Remove headlight (Low Beam).
(f) Disconnect connector.
(g) Remove front bumper. ( BO±12)
(h) Remove the bolt.
(i) Remove headlight (High±Beam).
2. INSTALL HEADLIGHT For installation, follow the removed procedure in reverse.
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BODY ELECTRICAL SYSTEM Lighting SystemBE±37
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Parts Replacement ± Taillights
(Clearance Light)
REPLACEMENT OF CLEARANCE LIGHT
(See page BE±37)
HINT: Replacement of Headlight (LO±Beam).
(FRONT SIDE MARKER LIGHT)
REPLACEMENT OF FRONT SIDE
MARKER LIGHT
1. REMOVE FRONT SIDE MARKER LIGHT (a) Disconnect negative (±) terminal from the battery.
CAUTION: Work must be started after approx.20
seconds from the time the ignition switch is turned to the
ºLOCKº position and negative (±) terminal cable is
disconnected from the battery.
(b) Remove fender liner. BO±92)
(c) Remove two nuts.
(d) Remove front side marker light from bumper.
(e) Disconnect connector.
2. INSTALL FRONT SIDE MARKER LIGHT For installation, follow the removal procedure in reverse.
(Light Failure Sensor)
See page BE±62
(Integration Relay)
See page BE±49
(Rear Combination Assembly)
REPLACEMENT OF REAR
COMBINATION LIGHT ASSEMBLY
1. REMOVE REAR COMBINATION LIGHT ASSEMBLY
(a)Disconnect negative (±) terminal from the battery.
CAUTION: Work must be started after approx. 20
seconds from the time the ignition switch is turned to the
ºLOCKº position and negative (±) terminal cable is
disconnected from the battery.
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BODY ELECTRICAL SYSTEM Lighting SystemBE±55
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(b) Remove the luggage compartment trim.
(c)Disconnect connector.
(d) Remove four nuts and rear combination light assembly.
2. INSTALL REAR COMBINATION LIGHT ASSEMBLY Follow the removal procedure in reverse to carry out installa-
tion.
(License Plate Light)
REPLACEMENT OF LICENSE PLATE
LIGHT
1. REMOVE LICENSE PLATE LIGHT(a) Disconnect negative (±) terminal from the battery.
CAUTION: Work must be started after. 20 seconds from
the time the ignition switch is turned to the ºLOCKº posi-
tion and negative (±) terminal cable is disconnected from
the battery.
(b) Remove the rear bumper.
(c) Disconnect connector.
(d) Remove three screws and the license plate light.
2. INSTALL LICENSE PLATE LIGHT
Follow the removal procedure in reverse to carry out
installation.
BE±56
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BODY ELECTRICAL SYSTEM Lighting System
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Parts Replacement ± Stoplights
(Rear Combination Light)
(See page BE±56 )
(High Mount Stop Light)
REPLACEMENT OF HIGH MOUNT STOP
LIGHT
1. REMOVE HIGH MOUNT STOP LIGHT
(a) Disconnect negative (±) terminal from the battery.
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and negative (±) terminal
cable is disconnected from the battery.
(w/o Rear Spoiler)
(b) Separate the woofer speaker cover from package tray
trim.
(c) Disconnect connector.
(d) Remove woofer speaker cover.
(e) Remove five screws and separate the high mount stop light from woofer speaker cover.
(w/ Rear Spoiler)
(f) Separate the rear spoiler from the luggage door. (See page BO±106 )
(g) Remove three screws and separate the high mount stop
light from rear spoiler.
2. INSTALL HIGH MOUNT STOP LIGHT For installation, follow the removal procedure in reverse.
Parts Inspection± Stop Light System
(Stop Light Switch)
STOP LIGHT SWITCH
REMOVAL AND INSTALLATION OF STOP
LIGHT SWITCH
1. REMOVE STOP LIGHT SWITCH
(a) Remove instrument panel subassembly cover underNo.1 and brake pedal return spring.
(b) Disconnect connector.
(c) Remove a nut and switch.
2. ADJUSTMENT OF STOP LIGHT SWITCH (See page BR±4)
3. INSTALL STOP LIGHT SWITCH For installation, follow the removal procedure in reverse.
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BODY ELECTRICAL SYSTEM Lighting SystemBE±61
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Parts Replacement (Turn Signals)
(Cornering Light)
REPLACEMENT OF CORNARING LIGHT
1. REMOVE CORNARING LIGHT(a) Disconnect negative (±) terminal from the battery.
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and negative (±) terminal
cable is disconnected from the battery.
(b) Remove front under cover. (See page BO±92 )
(c) Remove a screw and two nuts.
(d) Remove cornaring light from bumper.
(e) Disconnect connector.
2. INSTALL CORNARING LIGHT For installation follow the removal procedure in reverse.
(Front Turn Signal Light)
REPLACEMENT OF FRONT TURN
SIGNAL LIGHT
(See page BE±37 )
HINT: Replacement of Headlight (LO±Beam)
(Rear Combination Light)
(See page BE±56 )
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BODY ELECTRICAL SYSTEM Lighting SystemBE±67
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(Luggage Compartment Door
Courtesy Switch)
REPLACEMENT OF LUGGAGE
COMPARTMENT DOOR COURTESY
SWITCH
1. REMOVE COURTESY SWITCH(a) Remove the opening trim.
(b) Remove a bolt and disconnect connector.
(c) Remove the switch.
2. INSTALL COURTESY SWITCH For installation follow the removal procedure in reverse.
INSPECTION OF LUGGAGE COURTESY
SWITCH
INSPECT LUGGAGE DOOR COURTESY SWITCH(Continuity)
Inspect the switch continuity between terminal and switch
body.
If operation is not as specified, replace the switch.
(Switch Circuit)
Disconnect the connector from the switch and inspect the
connector on the wire harness as shown.
Check forTester connectionConditionSpecified value
Voltage1±GroundConstantBattery positive voltage
If circuit is not as specified, inspect power source or wire har-
ness.
BE±82
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BODY ELECTRICAL SYSTEM Lighting System
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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
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SUPPLEMENTAL RESTRAINT SYSTEM GENERAL DESCRIPTION
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REPLACEMENT REQUIREMENTS
RS01D±07
In the following cases, replace the wire harness or connector.
wIf any part of the SRS wire harness or any connector has
been found to be faulty in troubleshooting.
w If any part of the SRS wire harness or any connector has
been found to be faulty during the check in items 2±(b)
or (c).
NOTICE:
w If the wire harness used in the SRS is damaged, replace
the whole wire harness assembly.
w When the connector to the WIRE HARNESS AND CON-
NECTORs can be repaired alone (when there is no
damage to the wire harness), use the repair wire specially
designed for the purpose.
SENSOR REPLACEMENT
REPAIR WIRE FOR FRONT AIRBAG
RS04A±01
Repair wire with 2 pressure±contact sleeves
(Part No. 82988±24010) has been prepared for exclusive
use in repairing connector damage etc. caused by frontal col-
lision of the vehicle.
When repairing the WIRE HARNESS AND CONNECTOR
connector on the wire harness side, always use the special
repair wire.
NOTICE: Do not replace the connector housing or termi-
nal only.
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 ªLOCKº posi-
tion and the negative (±) terminal cable is disconnected
from the battery.
(See page RS±2)
2. DISCONNECT WIRE HARNESS AT VEHICLE SIDE
(a) Remove the cover at the rear of the connector housing and expose the wire harness.
(b) Cut the wire harness behind the connector housing. HINT: The operation is performed more easily if the wire har-
ness is left as long as possible.
RS±48
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SUPPLEMENTAL RESTRAINT SYSTEM WIRE HARNESS AND CONNECTOR
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177
SRS AIRBAG
NOTICE: When inspecting or repairing the SRS AIRBAG, perform the operation in accord\
ance with the
following precautionary instructions and the procedure and precautions in the Repair Manual for the applicable
model year.

Malfunction symptoms of the airbag system are difficult to confirm, so the diagnostic codes become the most
important source of information when troubleshooting.
When troubleshooting the airbag system, always inspect the diagnostic codes before disconnecting the
battery.

Work must be started after 30 seconds or longer from the time the Ignition SW is set to the ªLOCKº 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 30 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 me\
mory system.
Then when work is finished, reset the clock and audio system as before.
When the vehicle has tilt and telescopic steering, power seat, outside r\
ear 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 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 a back±up \
power supply from outside the
vehicle.

When removing the steering wheel pad or handling a new steering wheel pad, keep the pad upper surfa\
ce
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.

Never use airbag parts from another vehicle. When replacing airbag parts\
, replace them with new parts.

Never disassemble or repair the steering wheel pad, center airbag sensor asse\
mbly or front airbag sensors.

Before repairing the body, remove the airbag sensors if during repair shocks are likely to be app\
lied to the
sensors due to vibration of the body or direct tapping with tools or oth\
er parts.

Do not reuse a steering wheel pad or front airbag sensors.
After evaluating whether the center airbag sensor assembly is damaged or not, decide whether or not to reuse
it. (See the Repair Manual for the method for evaluating the center airbag\
sensor assembly.)

When troubleshooting the airbag system, use a high±impedance (Min. 1\
0k W/V) tester.

The vehicle wiring harness exclusively for the airbag system is distinguish\
ed by corrugated yellow tubing, as
are the connectors.

Do not measure the resistance of the airbag squib.
(It is possible this will deploy the airbag and is very dangerous.)

If the wire harness used in the airbag system is damaged, replace the wh\
ole wire harness assembly.
When the connector to the airbag front sensors can be repaired alone (when \
there is no damage to the wire
harness), use the repair wire specially designed for the purpose.
(Refer to the Repair Manual for the applicable Model year for details o\
f the replacement method.)

INFORMATION LABELS (NOTICES) are attached to the periphery of the airbag componen\
ts. Follow the
instructions on the notices.
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