LEXUS SC400 1991 Service Repair Manual

Wiring and Connector Diagrams
Parts Inspection
(Liquid Crystal Inner Mirror)
REMOVAL AND INSTALLATION OF
LIQUID CRYSTAL INNER MIRROR
(See page BO±44)
INSPECTION OF LIQUID CRYSTAL
INNER MIRROR
INSPECT LIQUID CRYSTAL INNER MIRROR
(a) Using a screw driver, pry out the cover.
(b) Remove two screws and center visor.
(Operation)
(a) Connect the positive (+) lead from the battery to terminal
1 and the negative (±) lead to terminal 2.
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BODY ELECTRICAL SYSTEM Liquid Crystal Inner Mirror SystemBE±165
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(b) Press the mirror switch and check if the mirrors surfacerepeatedly becomes ºbrightº and ºdarkº.
If operation is not as specified, replace the liquid crystal inner
mirror.
(Circuit)
Disconnect the inner mirror connector and inspect the con-
nector on the wire harness side as shown.
Check forTester connectionConditionSpecified value
Voltage2±GroundConstantBattery voltage
Continuity1 GroundIgnition key setContinuityContinuity1±GroundIgnition key removedNo continuity
If circuit is not as specified, refer to BE±165 wiring diagram
and inspect the circuits connected to other parts.
(Key Unlock Warning Switch)
(See page BE±26)
Troubleshooting
You will find the cause of trouble more easily by properly using the table \
shown below. In this table, the numbers
indicate the order of priority of the cruses of trouble. Check each part in the \
order shown. If necessary, replace
the part.
See pageBE±4,21BE±165BE±26 ±±
TroubleParts
name
DOME FuseLiquid Crystal Inner MirrorKey Unlock Warning SwitchWire Harness
Liquid Crystal Inner Mirror does not operate.1234
BE±166±
BODY ELECTRICAL SYSTEM Liquid Crystal Inner Mirror System
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ELECTRIC TENSION REDUCER
SYSTEM
Parts Location
Wiring and Connector Diagrams
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BODY ELECTRICAL SYSTEM Electronic Tension Reducer SystemBE±167
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Parts Inspection
(Tension Reducer Solenoid)
REMOVAL AND INSTALLATION OF
TENSION REDUCER SOLENOID
(See page BO±71)
INSPECTION OF TENSION REDUCER
SOLENOID
INSPECT TENSION REDUCER SOLENOID
(Operation)
(a) Connect the positive (+) lead from the battery to terminal
2, and negative (±) lead to terminal 1.
(b) Pull the belt upward and check that the belt is slowly retracted when released.
(c) Disconnect the lead from the battery.
(d) Pull the belt upward and check that the belt is retracted
more quickly when released than in (b).
HINT: Do not tilt the retractor.
If the operation is not as specified, replace the front seat outer
belt assembly.
(Circuit)
Disconnect the tension reducer solenoid connector and in-
spect the connector on wire harness side as shown.
Check forTester connectionConditionSpecified value
Voltage2±GroundIgnition switchONBattery voltagegg
positionACC or LOCKNo voltage
Continuity1±GroundBuckle switch positionON (belt fastened)Continuityy
OFF (belt unfastened)No continuity
If the circuit is specified, replace the front seat outer belt as-
sembly.
If the circuit is not as specified, refer to BE±167 wiring dia-
gram, and inspect the circuits connected to other parts.
BE±168
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BODY ELECTRICAL SYSTEM Electric Tension Reducer System
WhereEverybodyKnowsYourName

(Buckle Switch)
REMOVAL AND INSTALLATION OF
BUCKLE SWITCH
1. REMOVE BUCKLE SWITCH(a) Remove the driver or front passenger's seat.
(b) Disconnect buckle switch connector.
(c) Remove seat belt inner with buckle switch.
2. INSTALL BUCKLE SWITCH For installation follow the removal procedure in reverse.
INSPECTION OF BUCKLE SWITCH
INSPECT BUCKLE SWITCH(Switch Continuity)
(a) Check that there is continuity between terminals on theswitch side connector with the switch ON (belt
fastened).
(b) Check that there is no continuity between terminals on the switch side connector with the switch OFF (belt
unfastened).
If operation is not as specified, replace the seat belt inner.
(Switch Circuit)
Disconnect the connector from switch and inspect the con-
nector on wire harness side as shown.
Check forTester connectionConditionSpecified value
Voltage2±GroundIgnition switch posi-ONBattery voltagegg
tionACC or LOCKNo voltage
Continuity1±GroundConstantContinuity
If the circuit is not as specified, refer to BE±167 wiring dia-
gram, and inspect the circuits connected to other parts.
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BODY ELECTRICAL SYSTEM Electric Tension Reducer SystemBE±169
WhereEverybodyKnowsYourName

Troubleshooting
You will find the cause of trouble more easily properly using the table sho\
wn below. In this table, the numbers
indicate the order priority of the causes of trouble. Check each part in the order shown. If necessary, replace
the part.
See pageBE±4,20BE±168BE±169 ±±
TroubleParts
name
GAUGE FuseTension Reducer SolenoidBuckle SwitchWire Harness
Tension Reducer does not operate.
(Driver's and Passenger's)12
Tension Reducer does not operate. (Only one side)213
BE±170±
BODY ELECTRICAL SYSTEM Electric Tension Reducer System
WhereEverybodyKnowsYourName

DEFOGGER SYSTEM
Description
The component parts of this system and their functions are described in the\
following table.
Parts NameFunction
DefoggerWhen over current flows in the defogger circuit, the Defogger fuse break\
s the circuit
to protect it against damage.
Defogger RelayThis relay is supplied with current from terminal IG1 of ignition switch\
(Ignition switch ON)
and switches large current from the defogger.
A/C Control Panel
Assembly

Defogger SwitchThe defogger switch is built into the A/C Control Panel Assembly. This switch is
supplied with current from the relay and fuse HTR. Grounds current from \
the defogger
relay, turning the defogger relay ON.
Defogger

Rear Window

Outer MirrorThese defoggers generate heat when current is supplied from the defogger\
relay.
Parts Location
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BODY ELECTRICAL SYSTEM Defogger SystemBE±171
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Wiring and Connector Diagrams
Parts Inspection
(Defogger Switch)
REMOVAL AND INSTALLATION OF AIR
CONDITIONER CONTROL PANEL
ASSEMBLY
(See Instrument Panel on page BO±111)
INSPECTION OF DEFOGGER SWITCH
INSPECT SWITCH OPERATION
(a) Connect the positive (+) lead from the battery to terminal
A6 and negative (±) lead to terminal A7.
(b) Connect the positive (+) lead from the battery to terminal
B10 through a 1.4 W test bulb.
BE±172
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BODY ELECTRICAL SYSTEM Defogger System
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(c) Turn the defogger switch ON and check that the testbulb and indicator light turn ON, then turn OFF after
about 15 minutes.
If operation is not as specified, replace the air conditioner
control panel assembly.
(Defogger Relay)
INSPECTION OF DEFOGGER RELAY
INSPECT RELAY CONTINUITY AND OPERATION
Terminal
ConditionConstant
Apple battery voltage to terminals 1 and 3.
If continuity is not as specified, replace the relay.
(Defogger Wires)
INSPECTION AND REPAIR OF
DEFOGGER WIRES
1. INSPECT DEFOGGER WIRES
NOTICE:
w VWhen cleaning the glass, use a soft, dry cloth, and wipe
the glass in the direction of the wire. Take care not to
damage the wires.
w VDo not use detergents or glass cleaners with abrasive
ingredients.
w VWhen measuring voltage, wind a piece of tin foil around
the top of the negative probe and press the foil against
the wire with your finger as shown.
(a) Turn the ignition switch ON.
(b) Turn the defogger switch ON.
(c) Inspect the voltage at the center of each heat wire as
shown.
VoltageCriteria
Approx. 5 VOkay (No break in wire)
Approx. 10 V or 0 VBroken wire
HINT: If there is approximately 10 volts, the wire is broken be-
tween the center of the wire and the positive (+) end. If there
is no voltage, the wire is broken between the center of the
wire and ground.
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BODY ELECTRICAL SYSTEM Defogger SystemBE±173
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(d) Place the voltmeter positive (+) lead against thedefogger positive (+) terminal.
(e) Place the voltmeter negative (±) lead with the foil strip
against the heat wire at the positive (+) terminal end and
slide it toward the negative (±) terminal end.
(f) The point where the voltmeter deflects from zero to several volts is the place where the heat wire is broken.
HINT: IF the heat wire is not broken, the voltmeter indicates
0 volts at the positive (+) end of the heat wire but gradually
increases to about 12 volts as the meter probe is moved to
the other end.
2. REPAIR DEFOGGER WIRES (a) Clean the broken wire tips with a grease, wax andsilicone remover.
(b) Place the masking tape along both sides of the wire to be repaired.
(c) Thoroughly mix the repair agent (Dupont paste No. 4817).
(d) Using a fine tip brush, apply a small amount to the wire.
(e) After a few minutes, remove the masking tape.
(f) Allow the repair to stand at least 24 hours.
(Mirror Defogger)
REMOVAL AND INSTALLATION OF
MIRROR ASSEMBLY
(See Outside Rear View Mirror on page BO±42).
BE±174
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BODY ELECTRICAL SYSTEM Defogger System
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