ignition switch LEXUS SC400 1991 Service Repair Manual

INSPECTION OF RELAY BLOCK NO. 4
AND NO. 5 RELAY BLOCK
1. INSPECT FUSE CIRCUITRemove the fuse from the relay block and inspect the con-
nector on relay block side as shown.
FuseCheck forTester connectionConditionSpecified value
STHTRVoltage2±GroundIgnition Switch Turn to ONBattery voltage
If the circuit is not as specified, refer to BE±15 wiring diagram
and inspect the circuits connected to other parts.
2. INSPECT RELAY CIRCUIT
Remove the relay from the relay block and inspect the con-
nector on junction block side as shown.
RelayCheck forTester connectionConditionSpecified value
HORNVoltage(8)±GroundConstantBattery voltage
IG MAIN(9)±Ground
(13)±GroundContinuity
CRNRNG LP(14)±GroundIgnition Switch Turned to ONBattery voltage
(15)±Ground
±
BODY ELECTRICAL SYSTEM Power SourceBE±23
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IGNITION SWITCH
Description
The ignition switch is supplied with power from the battery via a fusible l\
ink. Power is supplied to each fuse
and relay according to the position of the switch, whether ªCCº ``ONº or ªSTARTº. The key unlock warning
switch, which detects the set condition of the key, is built into this switch.
Parts Location
Wiring and Connector Diagrams
±
BODY ELECTRICAL SYSTEM Ignition SwitchBE±25
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Parts Inspection
(Ignition Switch and Key Unlock
Warning Switch)
REMOVAL AND INSTALLATION OF
IGNITION SWITCH AND KEY UNLOCK
WARNING SWITCH
1. DISCONNECT BATTERY TERMINALSCAUTION: 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.
2. REMOVE FOLLOWING PARTS: (See page BO±112)
w No. 1 under cover
w No. 1 lower finish panel
w Console box assembly
w Instrument panel lower center
3. REMOVE IGNITION SWITCH (a) Disconnect connector.
(b) Remove three screws and the switch from the keycylinder and wire harness clamp.
4. INSTALL IGNITION SWITCH For installation, follow the removal procedure in reverse.
INSPECTION OF IGNITION SWITCH AND
KEY UNLOCK WARNING SWITCH
1. INSPECT IGNITION SWITCH(Switch continuity)
Inspect the switch continuity between terminals.
Terminal
Switch position LOCKACC
ON
START
If continuity is not as specified, replace the switch.
BE±26
±
BODY ELECTRICAL SYSTEM Ignition Switch
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(Switch circuit)
Connect the switch connector and inspect the connector on
the wire harness side from the back side as shown.
Check forTester connectionConditionSpecified value
Voltage2±GroundIgnition switch turned to ONBattery voltage
3±GroundIgnition switch turned to ACC or ON
4±GroundConstant
5±GroundIgnition switch turned to START
6±GroundIgnition switch turned to ON
11±GroundConstant
If circuit is not as specified, inspect the switch or refer to
BE±25 wiring diagram and inspect the circuits connected to
other parts.
2. INSPECT KEY UNLOCK WARNING SWITCH
(Switch continuity)
Inspect the switch continuity between terminals.
Terminal
Switch position
ON
OFF
(Ignition Key removed)
(Ignition Key set)
If continuity is not as specified, replace the switch.
(Switch circuit)
Connect the switch connector and inspect the connector on
the wire harness side from the back side as shown.
Check forCheck connectionConditionSpecified value
Continuity10±GroundIgnition key removedNo continuity
Ignition key setContinuity
9±GroundConstantContinuity
If circuit is not as specified, inspect the switch or wire harness.
±
BODY ELECTRICAL SYSTEM Ignition SwitchBE±27
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System Description ± Headlights
DAYTIME RUNNING LIGHT SYSTEM
The Daytime Running Light (DRL) system is activated when engine is started (However, if the parking brake
lever is engaged when the engine is started, the DRL will not light up a\
fter the engine has started. Once the
parking brake is released, the DRL will then light up and will remain on regardless of operation of\
the parking
brake lever).
The DRL remain on until the ignition switch is turned off.
BE±30±
BODY ELECTRICAL SYSTEM Lighting System
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Operation example (Current flow table)
1. Daytime Running Light Lights Up
SwitchPosition
Ignition switchON (Engine running)
Light Control SwitchOFF
Headlight Dimmer SwitchLO or HI
Condition: Battery Voltage " (3) , (14)
2. Taillight Lights Up
SwitchPosition
Ignition SwitchOFF or ON
Light Control SwitchTAIL
Headlight Dimmer SwitchLO or HI
Condition: Battery Voltage " (3)
Continuity (16) " (17) " Ground
3. Headlight LO±Beam Lights Up
SwitchPosition
Ignition SwitchOFF or ON
Light Control SwitchHEAD
Headlight Dimmer SwitchLO
Condition: Battery Voltage " (3)
Continuity (16) " (17) " Ground
(18) " (17) " Ground
±
BODY ELECTRICAL SYSTEM Lighting SystemBE±31
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4. Headlight HI±Beam Lights Up
SwitchPosition
Ignition SwitchOFF or ON
Light Control SwitchHEAD
Headlight Dimmer SwitchHI
Condition: Battery Voltage " (3)
Continuity (20) " (21) " Ground
(18) " (17) " Ground
(16) " (17) " Ground
5. Headlight Flash
SwitchPosition
Ignition SwitchOFF or ON
Light Control SwitchOFF or TAIL or HEAD
Headlight Dimmer SwitchFLASH
Condition: Battery Voltage " (3)
Continuity (19) " (21) " Ground
(20) " (21) " Ground
BE±32±
BODY ELECTRICAL SYSTEM Lighting System
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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.
±
BODY ELECTRICAL SYSTEM Lighting SystemBE±37
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Parts Inspection ± Headlight System
(Combination Switch Assembly)
REMOVAL OF COMBINATION SWITCH
ASSEMBLY
1. REMOVAL FOLLOWING PARTS:(See page BO±112)
w No. 1 under cover
w No. 1 lower finish Panel
NOTICE:
w Turn the steering wheel and front wheels to the straight
ahead position.
w Turn the ignition switch to the OFF position, then remove
the battery negative terminal.
2. REMOVE STEERING WHEEL CENTER PAD
(a) Remove two covers.
(b) Using torx driver or wrench, remove the four torx screws.
Torx wrench T30 (09042±00010)
Torx driver T30 (09041±00030)
(c) Remove center pad and disconnect connector.
3. REMOVE STEERING WHEEL (a) Remove the steering nut.
(b) Using SST, remove steering wheel.
SST 09213±31021
4. REMOVE STEERING COLUMN COVER Remove three screws and steering column covers.
±
BODY ELECTRICAL SYSTEM Lighting SystemBE±39
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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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