warning LEXUS SC400 1991 Service Workshop Manual

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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(STOP LIGHT SYSTEM)
DESCRIPTION ± Stoplight System
The component parts of this system and their function are as shown in the f\
ollowing table.
 Parts Name\
 \
Function
 

Stop Light Switch
\
 
\

\

Creates a closed circuit for current from the STOP fuse when the brake pedal is depressed,
thus turning on the stop lights.
 


Light Failure Sen-
sor\
 
\

\

This sensor senses when a bulb in rear combination light is burnt out an\
d lights up a warning
light.
PARTS LOCATION ± Stoplight System
±
BODY ELECTRICAL SYSTEM Lighting SystemBE±59
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(TURN SIGNAL AND HAZARD WARNING
LIGHT SYSTEM)
Description ± TURN SIGNAL AND
HAZARD WARNING LIGHT SYSTEM
The component parts of this system and their function are as shown in the f\
ollowing table.
Parts NameFunction
Turn Signal SwitchSwitches current from the turn signal flasher to the left side or right \
side.
Hazard Warning
SwitchModifies the circuit to the flasher relay and turn signal switch in acco\
rdance with the
respective switch positions.
Turn Signal FlasherReceives current from the hazard warning switch and flashes the turn sig\
nal lights by
switching the current to the lights ON and OFF.
PARTS LOCATION ± TURN SIGNAL
±
BODY ELECTRICAL SYSTEM Lighting SystemBE±65
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WIRING AND CONNECTOR DIAGRAMS
Turn Signal and Hazard Warning Lights
BE±66±
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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
±
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INSPECTION OF HAZARD WARNING
SWITCH
INSPECTION HAZARD WARNING SWITCH(Continuity)
Inspect the switch continuity between terminals.
If continuity is not as specified, replace the switch.
(Switch Circuit)
Disconnect the switch connector and inspect the connection
on the wire harness side as shown.
Check forTester connectionConditionSpecified value
Voltage8±GroundConstantBattery positive voltage
10±GroundIgnition switchpositionLOCK or ACCNo voltage10±GroundIgnition switch positionONBattery positive voltage
*12±GroundLight control switchpositionOFFNo voltage*12±GroundLight control switch positionTAIL or HEADBattery voltage
Continuity*13±GroundConstantContinuity
5±GroundConstant*2Continuity
6±GroundConstant*2Continuity
*1: Illumination*2: There is resistance because this circuit is grounded through the bulb.\
If the circuit is not as specified, refer to BE±66 wiring diagram
and inspect the circuits connected to other parts.
±
BODY ELECTRICAL SYSTEM Lighting SystemBE±69
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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±
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Check forTester connectionConditionSpecified value
VoltageA14±GroundIgnition switchpositionLOCK or ACCNo voltageA14±GroundIgnition switch positionONBattery positive voltage
ContinuityA6±GroundConstantContinuity
(Washer Motor and Tank)
REMOVAL AND INSTALLATION OF
WASHER MOTOR AND TANK
1. REMOVE WASHER TANK AND WASHER MOTOR(a) Remove fender liner.
(b) Disconnect connector and hose.
(c) Remove three screws and tank.
(d) Separate tank and washer motor.
2. INSTALL WASHER TANK AND MOTOR For installation follow the removal procedure in reverse.
INSPECTION OF WASHER MOTOR
INSPECT WASHER MOTOR
(Operation)
Connect the positive (+) lead from the battery to terminal 2
and the negative (±) lead to terminal 1, check that the motor
operates.
NOTICE: There tests must be performed quickly (within
20 seconds) to prevent the coil from burning out.
If operation is not as specified, replace the motor.
(Circuit)
Disconnect the connector from the washer motor and inspect
the connector on harness side as shown.
Check forTester connectionConditionSpecified value
Continuity1±GroundPush washer switch ONContinuity
Voltage2±GroundTurn ignition switch ONBattery positive voltage
If circuit is not as specified, inspect wire harness, power
source or wiper switch.
(Window Washer Level Warning Switch)
(See page BE±124)
BE±92
±
BODY ELECTRICAL SYSTEM Wiper and Washer System
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DESCRIPTION
The combination meter has various meters and gauges which show the vehicle'\
s condition, warning lights which
monitor abnormalities in the vehicle and inform the driver, indicator lights which inform the driver of the condition
of each part of vehicle, and a function for illumination and brightness ad\
justment of meters and gauges.
The component parts of this system and their functions are described in \
the following table.
Parts NameFunction
SpeedometerThe speedometer needle moves in accordance with signals from the speed s\
ensor to
indicate the vehicle's speed.
TachometerThe tachometer needle moves in accordance with signals from the igniter \
to indicate the
engine's speed.
Water Temperatrue
GaugeThe water temperature gauge's needle moves in accordance with signals from the send-
er gauge and indicates the temperature of the engine coolant.
Fuel GaugeThe fuel gauge needle moves in accordance with signals from the sender g\
auge, indicat-
ing the amount of fuel remaining in the fuel tank.
OdometerThe odometer counts the total distance traveled by the vehicle in accord\
ance with pulse
signals from the speed sensor.
Twin Trip Switch
The twin trip meter counts the distance traveled by the vehicle in accor\
dance with pulse
signals from the speed sensor. It can be reset using a switch and can be used to switch
between trip meters A and B.
Circuit Plate
This plate contains the circuitry for each meter and gauge and for each \
warning light and
indicator light, as well as an internal engine oil level warning drive c\
ircuit, drive circuits for
the odometer and trip meter and brightness adjustment circuitry for each\
indicator.
Speed SensorMounted in the transmission, this sensor outputs pulse signals to the co\
mbination meter
in accordance with the speed of the output shaft.
Twin Trip SwitchOperation of this switch switches between the A and B trip meters and se\
nds reset sig-
nals to the combination meter.
Water
Temperature Sender
GaugeThis sender converts engine coolant temperatures to a resistance value i\
n signal form to
the combination meter.
Fuel Sender GaugeThis sender converts the level of fuel remaining in fuel tank to resista\
nce value and
sends the resistance value in signal form to combination meter.
Rheostat Light
Control VolumeIn order to adjust the degree of illumination of the combination meter, the resistance val-
ue of the built±in variable resistor is sent to the combination meter\
and rheostat light
control.
Fuel Level Warning
SwitchWhen the level of fuel remaining falls below a predetermined level, cont\
inuity is estab-
lished with this switch, which is built into the fuel sender gauge, caus\
ing a warning light
to light up.
Low Oil Pressure
Warning SwitchThis switch is mounted on the engine block. Continuity is established in\
this switch when
the oil pressure is low, causing a warning light to light up.
Integration Relay (Seat
Belt Warning Relay)
This relay receives current from fuse GAUGE and DOME and is connected to\
each
buckle switch, door courtesy switch, key unlock warning switch and warni\
ng light. As
part of the seat belt warning system, it sounds a chime and lights a war\
ning light when
seat belts are unfastened. As part of the key unlock warning system, it \
sounds a chime
when the set conditions are fulfilled.
Light Failure SensorThis sensor senses when a bulb in rear combination light is burnt out an\
d lights up a
warning light.
BE±96±
BODY ELECTRICAL SYSTEM Combination Meter
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