1991 LEXUS SC400 turn signal bulb

PREPARATION
SST (SPECIAL SERVICE TOOLS)
IllustrationPart No.Part NameNote
09213±31021
Crankshaft Pulley
Puller
For removing steering wheel
RECOMMENDED TOOLS
IllustrationPart No.Part NameNote
09082±00015TOYOTA
Electrical Tester
09041±0030Torx Driver
T30
For removing and installing steering wheel pad and
power window motor
09042±00010Torx Socket
T30For removing and installing steering wheel pad and
power window motor
EQUIPMENT
Part NameNote
Voltmeter
Ammeter
Ohmmeter
Test lead
ThermometerWater temperature sender gauge, Engine oil level, Warning switch, Seat heater
SyphonBrake fluid level warning switch
Oil bathEngine oil level warning switch
Bulb (1.4 W)Coolant level warning ECU
Bulb (3.4 W)Fuel sender, gauge, Seat belt warning relay
Bulb (21 W)Turn signal flasher relay
Dry cell batteryFuel sender gauge
Heat lightSeat heater
Hexagon wrench (6 mm)Power seat
BE±8±
BODY ELECTRICAL SYSTEM Preparation
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(HEADLIGHT SYSTEM)
Description ± Headlight System
The component parts of this system and their function are described in the \
following table.
Parts NameFunction
Light Control SwitchGrounds current from the headlight control relay and taillight control r\
elay via the
integration relay, switching each relay and supplying current to the appropriate bulbs
accordance with the switch position.
Dimmer SwitchGrounds current from the dimmer relay in accordance with the switch posi\
tion, turning
on the ºLO±Beamº or ºHI Beamº lights. In the case of º\
FLASHº it turns the heading
control relay and turns on the ºHI Beamº lights.
Headlight Control
RelayTurned on by signals from the light control switch, dimmer switch and run\
ning light
relay and supplies current to each bulb or headlight dimmer relay.
Headlight
Dimmer RelayReceives current from the headlight control relay, which switches the relay according
to the position of the dimmer switch and sends current to the headlight \
ºLO±Beamº
or ºHI Beamº.
Integration RelayCarries out ºLight Auto Turn±offº of the headlights and taillights and cuts off current to
the light control switch in accordance with signals from the GAUGE fuse \
and courtesy
switch.
Door Courtesy
Switch/Driver 'sDetects when the door is open and sends the appropriate signals to integ\
ration relay.
(Light Auto Turn±Off System)
Parking Brake
Switch
(CANADA)Detects when the parking brake lever is released and sends the appropria\
te signals to
daytime running light relay.
±
BODY ELECTRICAL SYSTEM Lighting SystemBE±29
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5. USAINSPECT COMBINATION SWITCH CIRCUIT
(a) Pull the spool body to forward and separate spool bodyfrom steering column.
(b) C onnect the wire harness side connector to the
combination switch and inspect wire harness side
connector from the back side as shown.
(Light Control Switch Circuit)
Check forTester connectionConditionSpecified value
ContinuityB4±GroundConstantContinuity
(Dimmer Switch Circuit)
Check forTester connectionConditionSpecified value
*1B7 GroundLight Control Switch PositionOFF or TAILNo voltage*1B7±GroundLight Control Switch PositionHEADBattery voltage
VoltageLow beamNo voltage
*1B9±GroundDimmer Switch PositionFlash or High
beamBattery voltage
ContinuityB18±GroundConstantContinuity
*1: USA
(Turn Signal Switch Circuit)
Check forTester connectionConditionSpecified value
VoltageA3±GroundHazard Warning Switch ONBattery voltage
e 0 V
Ignition Switch ON and turn
signal switch positionRightBattery voltage
e 0 V
A4±GroundHazard Warning Switch ONBattery voltage
e 0 V
Ignition Switch ON and turn
signal switch positionLeftBattery voltage
e 0 V
ContinuityA12±GroundConstantContinuity
(Cornaring Light Control Switch Circuit)
Check forTester connectionConditionSpecified value
VoltageA8±GroundLight control switch HEAD andLOBattery voltagegg
dimmer switch positionHI or FLASHNo voltage
ContinuityA10±GroundConstant*2 Continuityy
A11±GroundConstant*2Continuity
*2 There is resistance because this circuit is grounded through the bulb.
If the circuit is not as specified, refer to BE±34 wiring diagram
and inspect the circuits connected to other parts.
±
BODY ELECTRICAL SYSTEM Lighting SystemBE±47
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(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
±
BODY ELECTRICAL SYSTEM Lighting SystemBE±53
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Parts Inspection (Turn and Hazard)
(Combination Switch Assembly)
(See page BE±39)
HINT: Inspect turn signal light switch.
(Turn Signal Flasher)
REMOVAL AND INSTALLATION OF TURN
SIGNAL FLASHER
(See page BE±16 )
INSPECTION OF TURN SIGNAL
FLASHER
INSPECT TURN SIGNAL FLASHER
(Operation)
LHD Side
(a) Connect the positive (+) lead from the battery to terminal
1 and the negative (±) lead to 4.
(b) Connect the two turn signal light bulbs parallel to each other to terminals 3 and 4, check that bulbs flash.
RHD Side
(c) Connect the positive (+) lead from the battery to terminal
1 and the negative (±) lead to 2.
(d) Connect two turn signal light bulbs parallel to each other
to terminals 2 and 5, check that the bulbs flash.
HINT: The turn signal lights should flash 60 to 120 times per
minute.
If one of the front or rear turn signal lights has an open circuit,
the number of flashes will be more than 140 per minute.
If operation is not as specified, replace the flasher.
(Flasher Circuit)
(See page BE±23 )
(HAZARD WARNING SWITCH)
REMOVAL AND INSTALLATION OF
HAZARD WARNING SWITCH
1. REMOVE INSTRUMENT PANEL NO.2 REGISTER
ASSEMBLY
(See page BO±111 )
2. REMOVE HAZARD WARNING SWITCH Remove two screws and hazard warning switch from register.
3. INSTALL HAZARD WARNING SWITCH AND REGISTER
For installation, follow the removal procedure in reverse.
BE±68
±
BODY ELECTRICAL SYSTEM Lighting System
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TROUBLESHOOTING
Turn Signal and Hazard Warning Light
System
You will find the cause of trouble more easily using the table shown below. In this table, the numbers indicate
the order priority of the causes in trouble. Check each part in the order \
shown. If necessary, replace the parts.
See pagePart
name
Trouble
ªHazardº and ªTurnº do not light up.
The flashing frequency is abnormal.
Hazard warning light does not light up.
(Turn is normal.)
Hazard warning light does not light up
in one direction.
*  Turn signal does not light up.
*

Turn signal does not light up.
Turn signal does not light up in one direction.
Only one bulb does not light up.
*
: Combination Meter, Wiper and Washer do not operate.
*  : Combination Meter, Wiper and Washer are normal.
HAZ±HORN Fuse
TURN Fuse
Ignition Switch
Hazard Warning Switch
Turn Signal Flasher
Turn Signal Switch
Wire Harness
Bulb
BE±4
, 21
BE±4
, 20
BE±26
BE±68
BE±68
BE±46
BE±6
BE±70±
BODY ELECTRICAL SYSTEM Lighting System
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