battery replacement LEXUS SC400 1991 Service Repair Manual

PRECAUTIONS FOR VEHICLES
EQUIPPED WITH SRS AIRBAG
The LEXUS SC400 is equipped with an SRS (Supplemental Re-
straint System) airbag.
Failure to carry out service operations in the correct sequence
could cause the airbag system to unexpectedly deploy during serv-
icing, possibly leading to a serious accident.
Further, if a mistake is made in servicing the airbag system, it is pos-
sible the airbag may fail to operate when required.
Before performing servicing (including removal or installation of
parts, inspection or replacement), be sure to read the following
items carefully, then follow the correct procedure described in this
manual.
Locations of Airbag Components
1. 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 diag-
nostic codes before disconnecting the battery. (See page
AB±25)
2. Work must be started after approx. 20 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.
(The airbag system is equipped with a back±up power source
so that if work is started within 20 seconds of disconnecting
the negative (±) terminal cable of the battery, the airbag may be
deployed.)
IN±8±
INTRODUCTION Precautions for Vehicles Equipped with SRS Airbag
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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 con-
tents memorized by each memory system. Then when work
is finished, reset the clock and audio systems as before.
When the vehicle has power tilt and power telescopic steer-
ing, 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 operation is finished, it will be
necessary to explain this fact to the customer, 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 airbag does not deploy, the front airbag sensors and the steering wheel pad
should be inspected. (See page AB±9)
4. Never use airbag parts from another vehicle. When replacing parts, replace them with new parts.
5. Before repairs, remove the airbag sensors if shocks are likely
to be applied to the sensors during repairs.
6. The center airbag sensor assembly contains mercury. After
performing replacement, do not destroy the old part. When
scrapping the vehicle or replacing the center airbag sensor
assembly itself, remove the center airbag sensor assembly
and dispose of it as toxic waste.
7. Never disassemble and repair the front airbag sensors, center airbag sensor assembly or steering wheel pad in order
to reuse it.
8. If the front airbag sensors, center airbag sensor assembly or steering wheel pad have been dropped, or if there are cracks,
dents or other defects in the case, bracket or connector,
replace them with new ones.
9. Do not expose the front airbag sensors, center airbag sensor assembly or steering wheel pad directly to hot air or flames.
10. U s e a v o l t / o h m m e t e r w i t h h i g h i m pedance (10 kW/V
minimum) for troubleshooting of the electrical circuit.
11. Information labels are attached to the periphery of the airbag components. Follow the notices.
12. After work on the airbag system is completed, perform the
airbag warning light check (See page AB±30).
±
INTRODUCTION Precautions for Vehicles Equipped with SRS AirbagIN±9
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GENERAL DESCRIPTION
The LEXUS SC400 is equipped with an SRS (Supplemental Restraint System) a\
irbag.
Failure to carry out service operations in the correct sequence could cause the\
airbag system to unex-
pectedly deploy during servicing, possibly leading to a serious accident.
Further, if a mistake is made in servicing the airbag system, it is possible the\
airbag may fail to operate
when required.
Before performing servicing (including removal or installation of parts, insp\
ection or replacement), be
sure to read the following items carefully, then follow the correct procedure described in the repair
manual.
1. Malfunction symptoms of the airbag system are difficult to confirm, so the diagnostic codes become themost important source of information when troubleshooting.
When troubleshooting the airbag system, always inspect the diagnostic co\
des before disconnecting the
battery (See page AB±25).
2. Work must be started after approx. 20 seconds or longer from the time the ig\
nition switch is turned to the LOCK position and the negative (±) terminal cable is disconnec\
ted from the battery. (The
airbag system is equipped with a back±up power source so that if work is sta\
rted within 20 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 sys-
tems will be cancelled. So before starting work, make a record of the conten\
ts memorized by the audio
memory system. Then when work is finished, reset the audio systems as before a\
nd adjust 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 customer, 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 airbag does not deploy, the front airbag sensors and
the steering wheel pad should be inspected (See page AB±9).
4. Never use airbag parts from another vehicle. When replacing parts, replace them with new parts.
5. Before repairs, remove the airbag sensors if shocks are likely to be applied to the sensors during repairs.
6. Never disassemble and repair the front airbag sensors, center airbag sensor a\
ssembly or steering
wheel pad in order to reuse it.
7. If the front airbag sensors, center airbag assembly or steering wheel pa\
d have been dropped, or if there are cracks, dents or other defects in the case, bracket or conn\
ector, replace them with new
ones.
8. Do not expose the front airbag sensors, center airbag sensor assembly or\
steering wheel pad directly to hot air or flames.
9. Use a volt/ohmmeter with high impedance (10 kW/V minimum) for troubleshoo\
ting of the electrical circuit.
10. Information labels are attached to the periphery of the airbag components. Follow t\
he instructions
on the notices.
11. After work on the airbag system is completed, perform the airbag warning\
light check (See page AB±30 ).
AB±2
SRS AIRBAG
± General Description
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REPLACEMENT OF REPAIR WIRE
FOR FRONT AIRBAG SENSOR
Repair wire with two pressure±contact sleeves (Part No.
82988±50010) has been prepared for exclusive use in repairing
connector damage etc. caused by frontal collision of the vehicle.
When repairing the front airbag sensor connector on the wire har-
ness side, always use the special repair wire.
NOTICE: Do not replace the connector housing or terminal
only.
REPLACEMENT OF AIRBAG REPAIR
WIRE
CAUTION: Work must be started after approx. 20
seconds or longer from the time the ignition switch is
turned to the ªLOCKº position and the negative (±) termi-
nal cable is disconnected from the battery.
1. DISCONNECT WIRE HARNESS AT VEHICLE SIDE (a) Remove the cover at the rear of the connector housingand 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.
2. CONNECT FRONT AIRBAG SENSOR WIRE HARNESS AT
VEHICLE SIDE AND REPAIR WIRE
(a) Start s tripping at least 8 mm (0.31 in.) to 11 mm (0.43 in.)
away from the end of the existing harness at vehicle side
and also from the end of the repair wire.
NOTICE: Take care not to damage the wire when strip-
ping the wire harness lead. After finishing the operation,
visually inspect the wire. If there is any damage, perform
the operation again.
(b) O ve rla p th e two stri pped wire ends inside of the
pressure±contact sleeve as illustrated in the left.
HINT: The blue pressure±contact sleeve (Part No.
AB±20
SRS AIRBAG
± Replacement of Repair Wire for Front Airbag Sensor
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ON±VEHICLE REPAIR
AT06Y±04
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.
EXTENSION HOUSING
EXTENSION HOUSING REAR OIL SEAL
REPLACEMENT
AT0QW±01
1. DRAIN ATF
2. REMOVE FRONT EXHAUST PIPE AND HEAT INSULATOR
(See pages EG±204)
3. REMOVE PROPELLER SHAFT (See pages PR±6)
4. REMOVE TRANSMISSION OUTPUT FLANGE
(a) Using a hammer and chisel, loosen the staked part of the nut.
HINT: Shift the shift lever to the P position.
(b) Using SST, remove the nut.
SST 09060±20100
(c) Tap the output flange with a plastic hammer to remove it and 2 washers.
(d) Using a screwdriver, remove the oil seal from the output flange.
5. REMOVE EXTENSION HOUSING REAR OIL SEAL Using SST, remove the oil seal.
SST 09308±00010
AT±14
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION EXTENSION HOUSING
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PARTS REPLACEMENT
WIRELESS DOOR LOCK ECU REMOVAL
AND INSTALLATION
1. REMOVE WIRELESS DOOR LOCK ECU(a) Remove the rear seat.
(b) Remove the RH quarter trim panel.
(c) Disconnect the connectors.
(d) Remove the ECU.
2. INSTALL WIRELESS DOOR LOCK ECU For installation, follow the removal procedure in reverse.
WIRELESS DOOR LOCK ECU AND
TRANSMITTER REPLACEMENT
Disassembly and assembly of the wireless door lock ECU
and transmitter includes details of spare parts and replace-
ment procedure for defective parts found through trouble-
shooting.
Each part is a precision electronic component so handle with
care.
Destroy old ROM and transmitter to prevent reuse.
1. SPARE PARTS AND REPLACEMENT PROCEDURE FOR MALFUNCTIONING PARTS
(For malfunctioning transmitter)
(a) Prepare the new transmitter (with ROM).
(b) Remove the ECU from the vehicle.
(c) Remove the ROM from the ECU.
(d) Install the new ROM into the ECU.
(e) Install the ECU into the vehicle.
(f) Check that door lock remote control operation works.
(g) Cut the new key to the shape of the replaced key.
(For non±functioning battery)
(a) Prepare new battery (with O±ring).
(b) Remove battery and O±ring from transmitter.
(c) Install new battery and O±ring into transmitter.
±
BODY ELECTRICAL SYSTEM Wireless Door Lock Control SystemBE±449
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(For malfunctioning ECU)
(a) Prepare the new ECU (without ROM).
(b) Remove the ECU from the vehicle.
(c) Remove the ROM from the ECU.
(d) Install the ROM into the new ECU.
(e) Install the new ECU into the vehicle.
2. REMOVAL OF ROM FROM ECU (a) Remove the cover from the hole for ROM insertion.
(b) Using long nosed pliers, grasp the center of the print
board (ROM) and remove it.
NOTICE:
w When replacing the ROM, always disconnect the
ECU connector first.
w When removing the ROM, always grasp the board
and do not touch the IC parts or print wiring on the
board.
(c) Insert the new print board (ROM) along the rails on both sides and push it in with your finger until the terminal on
the end is completely inserted.
(d) Install the cover to the hole for ROM insertion.
3. REPLACEMENT OF BATTERY FOR TRANSMITTER (a) Remove the screw from the transmitter.
(b) Remove the cover.
BE±450
±
BODY ELECTRICAL SYSTEM Wireless Door Lock Control System
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Replacement of Fuse
HINT: If replacing the fuse, be sure to replace it with a fuse
with an equal amperage rating.
NOTICE:
1. Turn off all electrical components and the ignition switchbefore replacing a fuse. Do not exceed the fuse amperage
rating.
2. Always use a fuse puller for removing and inserting a fuse. Remove and insert straight in and out without
twisting. Twisting could force open the terminals too
much, resulting in a bad connection.
If a fuse continues to blow, a short circuit is indicated. The
system must be checked by a qualified technician.
HINT: The puller is located at Relay Block No. 2.
How to Inspect for System Inspection
This inspection precedure is a simple troubleshooting which
should be carried out on the vehicle during system operation
and is based on the assumption of system component
trouble (except for the wires and connectors, etc.).
Always inspect the trouble taking the following items into con-
sideration.
wGround point fault
w Open or short circuit of the wire harness
w Connector or terminal connection fault
w Fuse or fusible link fault
NOTICE:
1. This is an on±vehicle inspection during system
operation. Therefore, inspect the trouble with due regard
for safety.
2. If connecting the battery directly, be careful not to short circuit, and select the applicable voltage.
BE±4±
BODY ELECTRICAL SYSTEM General Information
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PRECAUTIONS
Take care to observe the following precautions when performing inspection\
s or removal and replacement
of body electrical related parts.
1. SRS AIR±BAG SYSTEM

Work must be started approx. 20 seconds after the ignition is set to the Loc\
k position and the negative
(±) terminal cable is disconnected from the battery. (See page AB±2)

When disconnecting any of the connectors in the SRS AIR±BAG system, be su\
re to Lock the ignition
switch and disconnect the battery negative (±) terminal first. Since the connectors are twin \
lock type
connectors, disconnect the connectors only after releasing the first stage lock.

When connecting SRS AIR±BAG system connectors, be sure to lock them secur\
ely. (If the connectors
are not locked securely, the system may not operate when needed.)

Always store the steering wheel pad with the pad surface facing upward. (Stor\
ing the pad with its
metallic surface up may lead to a serious accident if the air bag inflates for s\
ome reason.)

When installing the spiral cable, be sure the vehicle is in the straight ahe\
ad condition and confirm that
the spiral cable is in the neutral position when it is installed. (See pag\
e BE±40)

INFORMATION LABELS (NOTICE) are attached to the periphery of the air bag componen\
ts. Follow
the NOTICE.
2. MICRO COMPUTER PRESET DRIVING POSITION SYSTEM
Power Seat Control System
Power Mirror Control System
Power Tilt and Telescopic Steering System

If the battery negative (±) terminal is disconnected, the preset driv\
ing positions stored in memory are
erased, so be sure to note the positions and reset them after the battery termi\
nal is reconnected.
3. AUDIO SYSTEM

If the battery negative (±) terminal is disconnected, the preset AM, F\
M 1 and FM 2 stations stored in
memory are erased, so be sure to note the stations and reset them after the battery terminal is
reconnected.

If the battery negative (±) terminal is disconnected, the ºANTI±\
THEFT SYSTEMº will operate when
the terminal is reconnected, but the radio, tape player and CD player will \
not operate. Be sure to input
the correct ID number so that the radio, tape player and CD player can be o\
perated again.
±
BODY ELECTRICAL SYSTEM PrecautionsBE±7
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Replacement of Relays
REPLACEMENT OF RELAY IN RELAY
BLOCK NO. 1, NO. 4 and NO. 5
1. REMOVE FOLLOWING PARTS:(See page BO±112)
(a) No. 1 under cover.
(b) Door scuff plate.
(c) Floor carpet.
2. REMOVAL AND INSTALLATION OF RELAY
(a) Remove the junction block No. 1 set bolts.
(b) Disconnect connectors.
(c) Separate the relay block No. 4 and No. 5 from the junction block No. 1.
(d) For installation follow the removal procedure in reverse.
Replacement of Relay Block No. 2
(A)
REPLACEMENT OF RELAY BLOCK NO. 2
(A) IN RELAY BLOCK NO. 2
1. REMOVE RELAY BLOCK NO. 2 (A)
(a) Remove 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 the relay block No. 2 cover.
(c) Pry loose two locking lugs and remove the nut.
2. INSTALL RELAY BLOCK NO. 2 (A) For installation follow removal procedure in reverse.
BE±16
±
BODY ELECTRICAL SYSTEM Power Source
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