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(c) Turn the defogger switch ON and check that the test bulb andindicator 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
If continuity is not as specified, replace the relay.
(Defogger Wires)
INSPECTION AND REPAIR OF
DEFOGGER WIRES
1. INSPECT DEFOGGER WIRESNOTICE:
w When 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 Do not use detergents or glass cleaners with abrasive
ingredients.
w When 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.
Voltage Criteria
Approx. 5 VOkay (No break in wire) Approx. 10 V or 0 V Broken 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±53
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(d) Place the voltmeter positive (+) lead against the defoggerpositive (+) 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 Pub. No. RM260U2, page
BO±42)
BE±54
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Page 851 of 4087
INSPECTION OF MIRROR DEFOGGER
INSPECT MIRROR DEFOGGER
(a) Connect the positive (+) lead from the battery to terminal 7 (4)
and the negative (±) lead to terminal 8 (5).
(b) Check that the mirror becomes warm. HINT: It will take a short time for the mirror to become warm.
If the mirror does not become warm, replace the mirror as-
sembly.
( ): w/o Driving Position Memory
Troubleshooting
You will find the cause of trouble more easily using the table shown belo\
w. In this table, the number indicate
the order priority of the causes in trouble. Check each part in the order s\
hown. If necessary, replace the parts.
Refer to 1992 LEXUS SC300 Repair Manual (Pub. No. RM260U2)
See pageBE±4 , 20
BE±4 , 20
BE±4 , 22
BE±172
BE±173
BE±173
BE±174
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Page 852 of 4087

(TAILLIGHT SYSTEM)
Description ± Taillight System
The component parts of this system and their function are as shown in the f\
ollowing table.
Parts Name\
\
Function
Light Control Switch\
\
\
Grounds current from the taillight control relay via the integration rel\
ay, switching each relay
and supplying current to the appropriate bulbs accordance with the switc\
h position.
Taillight Control Relay\
\
Turned on by signals from the light control switch and supplies current t\
o each bulb.
Integration Relay
\
\
\
\
Carries out ºLight Auto Turn±Offº of the headlights, fog lights and taillights and cuts off cur-
rent to the light control switch in accordance with signals from the GAU\
GE fuse and door
courtesy switch.
Light Failure Sensor\
\
\
This sensor senses when a bulb in rear combination light is burnt out an\
d lights up a warning
light.
Integration Relay\
Integration Relay
(Daytime Running
\
\
Refer to
BE±30. (y g
Light Relay: CANADA)\
\
PARTS LOCATION ± Taillight System
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WIRING AND CONNECTOR DIAGRAMS ±
Taillight System
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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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Page 855 of 4087
(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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Page 856 of 4087
Parts Inspection ± Taillights
(Combination Switch Assembly)
(See page BE±46
HINT: Inspect light control switch.
(Taillight Control Relay)
REMOVAL AND INSTALLATION OF
TAILLIGHT CONTROL RELAY
(See page BE±16)
INSPECTION OF TAILLIGHT CONTROL
RELAY
INSPECT TAILLIGHT CONTROL RELAY
(Continuity)
Inspect relay continuity between terminals.
If continuity is not as specified, replace the relay.
(Relay Circuit)
(See page BE±20)
±
BODY ELECTRICAL SYSTEM Lighting SystemBE±57
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