ignition LEXUS SC300 1991 Service Repair Manual

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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Check forTester connectionConditionSpecified value
Continuity1±GroundConstantContinuity
Voltage2±GroundWiper switch position
(I iti it h ON)
HIGH or MISTBattery positive voltage2±Ground(Ignition switch ON)OFF or INT, LOWNo voltage
3±GroundWiper switch position
(I iti it h ON)
LOW and MISTBattery positive voltage3±Ground(Ignition switch ON)OFF or INT, HIGHNo voltage
6±GroundIgnition switchLOCK or ACCNo voltage6±GroundONBattery positive voltage
If circuit is not as specified, refer to BE±86 wiring diagram and
inspect the circuits connected to other parts.
(Combination Switch)
INSPECT WIPER AND WASHER SWITCH
(See page BE±46)
(Continuity)
Inspect the switch continuity between terminals.
If continuity is not as specified, replace the switch.
(Resistance)
Inspect the switch resistance between terminals.
If resistance value is not as specified, replace the switch.
(Switch Circuit)
Disconnect the switch and wiper relay connector, inspect
each connector on the wire harness side as shown.
±
BODY ELECTRICAL SYSTEM Wiper and Washer SystemBE±91
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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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TROUBLESHOOTING
You will find the cause of trouble more easily by properly using the table \
shown below. In this table, the num-
bers indicate the order priority of causes of trouble. Check each part in th\
e order shown. If necessary, re-
place the parts.
See pageB±4,21BE±26BE±4,20BE±91BE±90BE±92BE±91BE±93±
Trouble
Part Name
AM1 FuseIgnition SwitchWIPER FuseWiper SwitchWiper MotorWasher MotorWasher SwitchWasher Hose and NozzleWire Harness
Wipers and washers do not operate.*1132456
Wipers and washers do not operate.*221345
Wipers and washers do not operate.*31234
Wipers do not operate in LO, HI or MIST.123
Wipers do not operate in INT.123
Washer motor does not operate.213
Wipers do not operate when washer switch
is ON.12
Washer fluid does not spray.1
*1: Door Lock and Power Windows do not operate
*
2: Door Lock and Power Window are normal. Combination Meter and Turn Signal do not operate.
*
3: Combination Meter and Turn Signal are normal.
BE±94
±
BODY ELECTRICAL SYSTEM Wiper and Washer System
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Parts Inspection
(Combination Meter Assembly)
REMOVAL AND INSTALLATION OF
COMBINATION METER ASSEMBLY
1. REMOVE COMBINATION METER ASSEMBLY(a) Lower the steering wheel fully and set it in the far position.
(b) Turn the ignition switch to LOCK and disconnect battery terminals.
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.
(c) Remove instrument cluster finish panel.
(d) Remove four screws and disconnect three connectors.
(e) Remove combination meter assembly.
2. INSTALL COMBINATION METER ASSEMBLY For installation, follow the removal procedure in reverse.
±
BODY ELECTRICAL SYSTEM Combination MeterBE±103
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ConnectionCheck forTester connectionConditionSpecified value
A19 A15Trip switch A/BPushContinuity
Trip switchContinuity
A19±A15Trip switch A/BFreeNo continuityTrip switchContinuity
A20 A15Trip switch RESETPushContinuityA20±A15Trip switch RESETFreeNo continuity
DOME
FuseVoltageA11±GroundConstantBattery positive voltage
Speed
SVoltageA13 A15
Ignition
switch
*3 Revolve propeller shaft0V
11 V
SensorVoltageA13±A15switch
ON*3 Stop propeller shaft0V or 11V
C1±GroundPBattery positive voltage
C2±GroundIgnitionRBattery positive voltage
Neutral start
it hVoltageC3±Ground
Ignition
switch
ON andNBattery positive voltageswitchVoltageC4±GroundON and
shift leverDBattery positive voltage
C5±Ground
shift lever
position2Battery positive voltage
C16±Ground
osition
LBattery positive voltage
O/D OFFContinuityC18 GroundO/D OFF switchONContinuity
SwitchContinuityC18±GroundO/D OFF switchOFFNo continuity
AlternatorContinuityC15±GroundEngine stopContinuity
ºLº terminalVoltageC14±GroundEngine runningBattery positive voltage
FuelContinuityA7 GroundFuel remainderFullNo continuity
SenderContinuityA7±GroundFuel remainderEmptyContinuity
GaugeFull, Approx. 79.3 mm
(3.12 in.)Approx. 6

ResistanceA8±C8Float
position1/2, Approx. 193.1 mm
(76.0 in.)Approx. 32.5

Empty, Approx. 308.1 mm
(12.13 in.)Approx. 97

*Window
washer level
ContinuityB9±GroundON (float down)Continuitywasher level
warning
switchContinuityB9 Ground
(Canada)OFF (float up)No continuity
Brake fluidBrake fluid levelON (float down)Continuity
Level warning
Brake fluid level
warning SWOFF (float up)No continuity
SW and
Parking brake
SW
ContinuityC13±GroundParking brake
ON (Depress the Ped-
al))Continuity
SWParking brake
SWOFF (Release the Ped-
al)No continuity
Low oil
PressureContinuityC19 GroundEngine condition
RunningNo continuity
Pressure
Warning SWContinuityC19±GroundEngine conditionStopContinuity
Door courtesyContinuityC12 GroundDriver's andOpen (ON)Continuityy
SwitchContinuityC12±GroundDriver s and
passenger's doorClosed (OFF)No continuity
IGN fuseVoltageC14 GroundIgnition switchONBattery positive voltageVoltageC14±GroundIgnition switchLOCK or ACCNo voltage
CIG fuseVoltageA6 GroundIgnition switchACC or ONBattery positive voltageVoltageA6±GroundIgnition switchLOCK or STARTNo voltage
BE±107±
BODY ELECTRICAL SYSTEM Combination Meter
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ConnectionCheck forTester connectionConditionSpecified value
Turn signalHazard warning switch ONBattery positiveTurn signal
SW andB 16 Ground
Hazard warning switch ONBattery ositive
voltage e 0V
HazardB±16±Ground
IG SW ON and turn signal SW ºLeftºBattery positive
Warning
Si hVoltage
IG SW ON and turn signal SW ºLeftºBattery ositive
voltage e 0V
SwitchVoltage
Hazard warning switch ONBattery positive
B 17 Ground
Hazard warning switch ONBattery ositive
voltage e 0VB±17±Ground
IG SW ON and turn signal SW ºRightºBattery positiveIG SW ON and turn signal SW ºRightºBattery ositive
voltage e 0V
HeadlightLi ht t l SWDimmer SW ºHIº orBattery positiveHeadlight
VoltageB7±GroundLight control SW
ºHEADº
Dimmer SW HI or
ºFlashº
Battery ositive
voltageVoltageB7±GroundºHEADºDimmer SW ºLOºNo voltage
ContinuityB6±GroundLight control SW
º
HEADº
Dimmer SW ºHIº or
ºFlashºContinuityContinuityB6 GroundºHEADºDimmer SW ºLOºNo continuity
IgniterVoltageA9±GroundEngine RunningVoltage
fluctuates
ECT patternVoltageB4 GroundIG SW ON and ECT patternPWRBattery positive voltageECT attern
Select switchVoltageB4±GroundIG SW ON and ECT attern
select SW positionNORMNo voltage
Engine oilOil temperature below approx. 55 5C (131 5F)Continuityg
Level warn-
ing Switch
ContinuityB8±Ground
Oil temperature
above approx. 55 5CON (float up)ContinuitygContinuityB8 Groundabove a rox. 55 C
(131 5F) and SW
positionOFF (float off)No continuity
GAUGE fuseVoltageA1 GroundIgnition switchONBattery positive voltageVoltageA1±GroundIgnition switch
positionLOCK, ACC, STARTNo voltage
Neutral StartVoltageA12±GroundIgnition switch
position
START (ºPº or ºNº
range)Battery positive voltage
switch
VoltageA12 GroundpositionLOCK, ACC, ONNo voltage
ECU±BVoltageC11 GroundIgnition switchONBattery positive voltage
FuseVoltageC11±GroundIgnition switch
positionLOCK, ACC, STARTNo voltage
Rheostat
Li ht t l
ON (Rheostat knob
t d itiBtt ltLight control
VolumeLight control SWturned any position
except fully clock-
Battery voltage or
5V or moreVolume
VoltageA2±Ground
g
HEAD or TAIL and
rheostat volume
except fully clock-
wise)5V or more
VoltageA2 Groundrheostat volume
knob positionOFF (Rheostat knob)
turned fully clockNo voltageknob ositionturned fully clock-
wise)No voltage
GroundA8±GroundConstantContinuity
ContinuityA10±GroundConstantContinuityContinuityA22±GroundConstantContinuity
A23±GroundConstantContinuity
*1 Jack up the vehicle.*2 Shift lever position is ºPº range.
If circuit is not as specified, refer to BE±100 wiring diagrams
and inspect the circuits connected to other parts.
BE±108
±
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(Speed Sensor)
REMOVAL AND INSTALLATION OF
SPEED SENSOR
1. REMOVE SPEED SENSOR(a) Jack up the vehicle.
(b) Disconnect connector and control rod.
(c) Remove a bolt and sensor.
2. INSTALL SPEED SENSOR For installation, follow the removal procedure in reverse.
INSPECTION OF SPEED SENSOR
INSPECT SPEED SENSOR(Operation)
(a) Connect the positive (+) lead from battery to terminal 1and negative (±) lead to terminal 2.
(b) Connect the positive (+) lead from tester to terminal 3 and negative (±) lead to terminal 2.
(c) Revolve shaft.
(d) Check that there is voltage change from approx. 0V to 11V or more between terminal 2 and 3.
HINT: The voltage change should be 4 times per each revolu-
tion of the speed sensor shaft.
If operation is not as specified, replace the sensor.
(Sensor circuit)
Disconnect connector from sensor and inspect the connector
on wire harness side as shown.
Check forTester connectionConditionSpecified value
Voltage1 GroundIgnition switchONBattery positive voltageg1±GroundIgnition switch
positionLOCK or ACCNo voltage
If circuit is not as specified, inspect power source or wire
harness.
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BODY ELECTRICAL SYSTEM Combination MeterBE±110
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DIAGNOSIS SYSTEM
INDICATOR CHECK
When the ignition switch is turned on, check that the TRAC
indicator light goes on for 3 seconds.
HINT: If the indicator check result is not normal, proceed to
troubleshooting for the TRAC indicator light circuit (see page
BR±225 ).
DIAGNOSTIC TROUBLE CODE CHECK
1. Turn the ignition switch ON.
2. Using SST, connect terminals Tc and E1 of DLC2 or DLC 1.
SST 09843±18020
3. Read the diagnostic trouble code from the TRAC indicator light on the combination meter.
HINT: If no code appears, inspect the diagnostic circuit or
TRAC indicator light circuit ( BR±226 orBR±225 ).
As an example, the blinking patterns for normal code and
codes 11 and 21 are shown on the left.
4. Codes are explained in the code table on the next page.
5. After completing the check, disconnect terminals Tc and
E1, and turn off the display.
If two or more malfunctions are indicated at the same time,
the lowest numbered diagnostic trouble code will be dis-
played 1st.
ECU DATA MONITOR USING LEXUS
HAND±HELD TESTER
1. Hook up the LEXUS hand±held tester to the DLC2.
2. Monitor the ECU data by following the prompts on thetester screen.
HINT: LEXUS hand±held tester has a ªSnapshotº function
which records the monitored data.
Please refer to the LEXUS hand±held tester operator's
manual for further details.
BR±170
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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The speed sensor detects the wheel speed and sends the ap-
propriate signals to the ECU. These signals are used for control
of both the ABS and TRAC control systems. The front and rear
rotors each have 48 serrations. When the rotors rotate, the mag-
netic field emitted by the permanent magnet in the speed sensor
generates an AC voltage. Since the frequency of this AC voltage
changes in proportion to the speed of the rotors (wheels), the
frequency is used by the ECU to detect the speed of each wheel.
BR3583
BR3582
DTC31, 32,
33, 34Speed Sensor Circuit
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
31, 32,
33, 34
Detection of any of conditions (1) through (3):
(1) At vehicle speed of 10 km/h (6 mph) or more, pulses are not input for 5 sec.
(2) Momentary interruption of the vehicle speed sen- sor signal occurs at least 7 times in the time be-
tween switching the ignition switch ON and switch-
ing it OFF.
(3) Abnormal fluctuation of speed sensor signals with the vehicle speed 20 km/h (12 mph) or more.

Right front, left front, right rear and left rear
speed sensor.

Open or short in each speed sensor circuit.

ECU
Hint: DTC No. 31 is for the right front wheel speed sensor.
DTC No. 32 is for the left front wheel speed sensor.
DTC No. 33 is for the right rear wheel speed sensor.
DTC No. 34 is for the left rear wheel speed sensor.
Fail safe function: If trouble occurs in the speed sensor circuit, the E\
CU prohibits TRAC control.
BR±190
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BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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