lights LEXUS SC400 1991 Service User Guide

DIAGNOSIS SYSTEM
AT09R±07
The electronically controlled transmission system has built±
in self±diagnostic functions. If the malfunction occurs in the
system, the ECM stores the malfunction code in memory and
the O/D OFF (Overdrive OFF) indicator light blinks to inform
the driver. The diagnostic trouble code stored in memory can
be read out by the following procedure.
O/D OFF INDICATOR LIGHT INSPECTION
AT09S±07
1. Turn the ignition switch to ON.
2. Check if the O/D OFF indicator light lights up when the O/D main switch is pushed out to OFF and goes off when
the O/D main switch is pushed in to ON.
HINT:
wIf the O/D OFF indicator light does not light up or stay on
all the time, carry out the check for ªO/D OFF Indicator
Light Circuitº on page AT±112.
w If the O/D OFF indicator light blinks, a trouble code is
stored in the ECM memory.
DIAGNOSTIC TROUBLE CODE CHECK
AT0A3±07
1. Turn the ignition switch ON, but do not start the engine.
2. Push in the O/D main switch to ON.
HINT: Warning and diagnostic trouble codes can be r ead only
when the O/D main switch is ON. If it is OFF, the O/D OFF indi-
cator lights up continuously and will not blink.
3. Using SST, connect terminals TE1 and E1 of the DLC2 or
DLC1.
SST 09843±18020
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±37
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INSPECTION PROCEDURE
1Check operation of stop light.
Check if the stop lights go on and off normally when the brake pedal is operated and released.C
Check and repair stop light circuit (See BE section).
2Check stop light signal.
C
OK
1. Connect voltmeter to the terminals TT and E1 of the
DLC2.
2. Turn ignition switch ON (Do not start the engine).
3. Fully depress the accelerator pedal until the volt- meter indicates 8 V and hold it.
4. Depress and release the brake pedal and check the
voltage.
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
3Check harness and connector between ECM and stop light switch (See page\
IN±33).
Repair or replace harness or connector.
Check and replace ECM.
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±109
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WIRING DIAGRAM
O/D Main Switch and O/D OFF Indicator Light Circuit
CIRCUIT DESCRIPTION
The O/D main switch contacts go off when the switch is pushed in and comes on when it is pushed out.
In O/D main switch OFF position, the O/D OFF indicator lights up, and the \
ECM prohibits shifting to over-
drive. The ECM also causes the O/D OFF indicator light to blink when a malfunc\
tion is detected. In this
case, connecting the terminals in the DLC2 or DLC1 can display the malfu\
nction code.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
See next page.
AT±112
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INSPECTION PROCEDURE
1Check operation of O/D Main Switch
C
OK
Hint
C
OK
1. Turn ignition switch ON.
2. Check ªO/D OFFº light when O/D main switch ispushed in to ON.
ªO/D OFFº light goes off.
3. Check ªO/D OFFº light when O/D main switch is pushed again, to OFF.
ªO/D OFFº light lights up.
If the ªO/D OFFº lights blinks when the O/D main switch
is pushed in to ON, a malfunction is occurring in the sys-
tem.
Check the diagnostic trouble code.
Go to step
.
2Check voltage between terminal OD2 of ECM connector and body ground.
C
OK
P1. Connect the check harness A to the ECM (See EG
section).
2. Turn ignition switch ON.
Check voltage between terminal OD2 of ECM and body
ground
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
3Check harness and connector between O/D off indicator light and ECM (Se\
e page IN±33).
Repair or replace harness or connector.
Check and replace ECM.
AT±114±
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INSTALLATION OF FRONT BUMPER
(See page BO±11)
INSTALL FRONT BUMPER PARTS BY FOLLOWING RE-
MOVAL SEQUENCE IN REVERSE HINT:
wWhen installing the bumper on the body, be careful
not to damage the serrated part of side bolts.
wAfter installing the headlight, adjust the light aiming.
(See page BE±38).
DISASSEMBLY AND ASSEMBLY OF
FRONT BUMPER
DISASSEMBLY AND ASSEMBLY BY
FOLLOWING PARTS:
(a) Cornering lights
(b) Side turn lights
(c) Bumper energy absorber
(d) Retainers
(e) License bracket
BO±14
±
BODY Bumper (Front Bumper)
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2. INSPECT BRAKE WARNING LIGHT(a) Disconnect the connector from the brake fluid warningswitch.
(b) Release the parking brake pedal.
(c) Connect terminals on the wire harness side of the level warning switch connector.
(d) Start the engine, check that the warning light lights up.
If the warning light does not light up, test the bulb or wire har-
ness.
(Parking Brake Switch)
REMOVAL AND INSTALLATION OF PARKING
BRAKE SWITCH
1. REMOVE PARKING BRAKE SWITCH
(a) Remove the driver's seat.
(See page BO±58)
(b) Disconnect the connector and remove switch.
2. INSTALL PARKING BRAKE SWITCH For installation follow the removal procedure in reverse.
INSPECTION OF PARKING BRAKE SWITCH
1. INSPECT PARKING BRAKE SWITCH
(a) Check that there is continuity between terminal andswitch body with the switch ON (switch pin released).
(b) Check that there is no continuity between terminal and switch body with the switch OFF (switch pin pushed in.)
If continuity is not as specified, replace the switch or inspect
ground point.
2. INSPECT BRAKE WARNING LIGHT (a) Disconnect the connector from the parking brake switchand brake fluid warning switch.
(b) Ground terminal on the wire harness side connector.
(c) Start the engine, check that the warning light lights up.
If the warning light does not light up, test the bulb or inspect
wire harness.
BE±116
±
BODY ELECTRICAL SYSTEM Combination Meter
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( Coolant Level Warning Switch)
REMOVAL AND INSTALLATION OF COOLANT
LEVEL WARNING SWITCH
1. REMOVE COOLANT LEVEL WARNING SWITCH(a) Disconnect the connector.
(b) Remove the boot.
(c) Using the notches in the head of switch, turn the switchcounterclockwise and remove it.
NOTICE: Do not remove when engine is hot.
2. INSTALL COOLANT LEVEL WARNING SWITCH For installation, follow the removal procedure in reverse.
INSPECTION OF COOLANT LEVEL WARNING
SWITCH
1. INSPECT COOLANT LEVEL WARNING SWITCH(Continuity)
(a) Remove the radiator cap and open the radiator drainclock.
NOTICE: Do not remove when engine is hot.
(b) Drain the coolant about 1 liter. (1.1 US qts, 0.9 lmp. qts)
(c) Check that there is continuity between terminals (float down).
(d) Close radiator drain cock and fill the cooling system with
coolant.
(e) Check that there is no continuity between terminals (float up).
If continuity is not as specified, replace the switch.
2. INSPECT COOLANT LEVEL WARNING LIGHT (a) Disconnect the connector from the coolant level warning
switch and ground terminal 1 on the wire harness side
connector.
(b) Start the engine, check that the warning light lights up.
If the warning light does not light up, inspect the bulb or wire
harness.
±
BODY ELECTRICAL SYSTEM Combination MeterBE±117
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Parts Inspection
(Power Switch)
REMOVAL AND INSTALLATION OF
POWER SWITCH
1. REMOVAL CONTROL PANEL(a) Remove the console upper panel.(See BO section)
(b) Remove three screws and the control panel.
2. INSTALL CONTROL PANEL For installation, follow the removal procedure in reverse.
INSPECTION OF POWER SWITCH
INSPECT POWER SWITCH
(Continuity)
Inspect continuity between terminals.
Terminal
Switch position
OFF (Power switch released) ON (Power switch pushed in)
If continuity is not as specified, replace the control panel.
(Resistance)
Inspect resistance between terminals.
Tester connectionConditionSpecified value
11±13ConstantApprox. 50 k 
11±14Switch knob
A
BApprox. 0
50 k 
If resistance is not as specified, replace the control panel.
(Illumination)
Connect the positive (+) lead from the battery to terminal 2
and the negative (±) lead to terminal 1, check that the illu-
mination light lights up.
If the illumination light does not light up, replace the control
panel.
BE±206
±
BODY ELECTRICAL SYSTEM Audio System
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INSPECTION PROCEDURE
1Check the shift position indicator.
Check that P lights up on the shift indicator when P range is shifted in\
to, and that P is OFF when
shiftin
g into another range.
C
Check shift position indicator circuit (See page BE±141).
2Check voltage between terminal P of ECU connector and body ground.
C
OK
PRemove ECU with connectors still connected.
(1) Turn ignition switch ON.
(2) Measure voltage between terminal P of ECU con-nector and body ground when the shift lever is posi-
tioned to the following ranges.
Shift range
P
1
0
Other than PVoltage
10 ± 14 V
Below 1 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±276).
Check and repair harness and connector between
ECU and connector.
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BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)BE±301
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Check for Voltage
(a) Establish conditions in which voltage is present at thecheck point.
Example:
(A)±Ignition SW on
(B)±Ignition SW and SW 1 on
(C)±Ignition SW, SW 1 and Relay on (SW 2 off)
(b) Using a voltmeter, connect the negative (±) lead to a good ground point or negative (±) battery terminal and
the positive (+) lead to the connector or component
terminal. This check can be done with a test bulb instead
of a voltmeter.
Check for Continuity and Resistance
(a) Disconnect the battery terminal or wire so there is no voltage between the check points.
(b) Connect the two leads of an ohmmeter to each of the check points.
If the circuit has diodes, reverse the two leads and check
again.
When contacting the negative (±) lead to the diode positive
(+) side and the positive (+) lead to the negative (±) side,
there should be continuity. When contacting the two leads in
reverse, there should be no continuity.
HINT: Specifications may vary depending on the type of tes-
ter, so refer to the tester's instruction manual before perform-
ing the inspection.
Check LED (Light Emitting Diode) in the same manner as that
for diodes.
HINT:
w Use a tester with a power source of 3 V or greater to
overcome the circuit resistance.
w If a suitable tester is not available, apply battery voltage
and check that the LED lights up.
±
BODY ELECTRICAL SYSTEM General InformationBE±5
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