ignition system LEXUS SC400 1991 Service Service Manual

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
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±37
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4. Read the diagnostic trouble code indicated by thenumber of times the O/D OFF indicator light blinks.
HINT: If the system is operating normally, the light will blink
2 times per second.
The malfunction code is indicated as shown in the illustration
at left (Diagnostic trouble code ª42º is shown as an example).
HINT: When 2 or more trouble codes are stored in memory,
the lower±numbered code is displayed first.
If no diagnostic trouble code is output, or if a diagnostic
trouble code is output even though no diagnostic trouble
code output operation is performed, check the TE1 terminal
circuit on page AT±118.
DIAGNOSTIC TROUBLE CODE CHECK
BY USING LEXUS HAND±HELD TESTER
AT0RD±01
1. Hook up the LEXUS hand±held tester to the DLC2.
2. Read the diagnostic trouble codes by following theprompts on the tester screen.
Please refer to the LEXUS hand±held tester operator's
manual for further details.
CANCELING DIAGNOSTIC TROUBLE
CODE
AT09T±07
After repair of the trouble area, the diagnostic trouble code
retained in the ECM memory must be canceled out by remov-
ing the EFI fuse for 10 seconds or more, with the ignition
switch off.
Check that the normal code is output after connecting the
fuse.
AT±38
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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ExampleGENERAL INFORMATION
HANDLING PRECAUTIONS
Taping
When it is possible that the body or parts may be scratched
during the operation, apply protection tape before starting
work.
Example:
1. Before starting work, apply protection tape to bodysurfaces around parts to be removed and installed.
2. Before prying parts loose with a screwdriver or scraper etc., apply protection tape to the tip of the tool to avoid
scratching parts or painted surfaces of the body.
Battery
In order to prevent a short circuit while doing work on the elec-
trical circuit such as disconnecting a connector, first turn off
the ignition switch and disconnect the negative cable from
the battery terminal before starting work.
HINT: When battery voltage is required for operation of a
functioning part, connect the cable to the battery when need-
ed, and promptly disconnect it when no longer necessary.
CAUTION:
wWork must be started after approx. 20 seconds or longer
from the time the ignition switch is turned to the ºLOCKº
position and the negative (±) terminal cable is
disconnected from the battery.
wTo avoid erasing the memory of each memory system,
never use a back±up power supply from outside the
vehicle.
Fitting Adjustments
When removing and installing body panels which have a pre-
load value, after the installation refer to the page containing
the installation adjustment methods, and make adjustments
according to the required specifications.
HINT: When making adjustments, do not completely loos-
en the bolts and nuts of the part being adjusted. T ighten them
appropriately, and move the panels by hand to align them.
BO±2
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BODY General Information
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SRS AIRBAG
(See page AB±2)
The LEXUS SC300 is equipped with an SRS (Supplemental Restraint System)\
airbag.
Failure to carry out service operations in the correct sequence could cause the airbag system to deploy,
possibly leading to a serious accident.
When removal or installation of airbag parts and the yellow wire harness\
and connector for the airbag is
necessary, refer to the precautionary notices in the AB section before performing\
the operation.

Work must be started after 20 seconds or longer from the time the ignition switch is set to the LOCK
position and the negative (±) terminal cable is disconnected from the batte\
ry.
(The airbag system is equipped with a back±up power source so that if wor\
k is started within 20 se-
conds of disconnecting the negative (±) terminal cable of the batte\
ry, the airbag may be deployed.

To avoid erasing the memory of each memory system, never use a back±up power supply from
outside the vehicle.

Before repairs, remove the airbag sensors if shocks are likely to be applied t\
o the sensors during
repaires.

The front airbag sensor set bolt has been anti±rust treated. When the\
sensor is removed, always
replace the set bolt with a new one.

If the front airbag sensors, center airbag sensor or steering wheel pad ha\
ve been dropped, or if there
are cracks, dents or other defects in the case, bracket or connector, replace them with new ones.

Never use airbag parts from another vehicle. When replacing parts, repla\
ce them with new parts.

Do not expose the front airbag sensors, center airbag sensor or steering w\
heel pad directly to hot air
or flames.

The airbag system's wire harness is integrated with the cowl wire harness assembly. The wires for the
airbag wire harness are encased in a yellow corrugated tube. All the connector\
s for the system are
also a standard yellow color. If the airbag system wire harness becomes disconnected or the
connector becomes broken due to an accident, etc., repair or replace it as shown \
on page AB±20.

The steering wheel must be fitted correctly to the steering column with the\
spiral cable at the neutral
position; otherwise, cable disconnection and other troubles may result. \
Refer to page AB±14 of this
manual concerning correct steering wheel installation.

When removing the steering wheel pad or handling a new steering wheel pad, i\
t should be placed with
the pad top surface facing up. In this case, the twin±lock type connector lock lever should be in the
locked state and care should be taken to place it so the connector will not be damaged. (\
Storing the
pad with its metallic surface up may lead to a serious accident if the a\
irbag inflates for some reason.)

Grease should not be applied to the steering wheel pad and the pad should not \
be cleaned with
detergents of any kind.

Store the steering wheel pad where the ambient temperature remains below 93 C (200 F), without
high humidity and away from electrical noise.

Information labels are attached to the periphery of the airbag component\
s. Follow the notices.

When the ignition switch is at ACC or ON and the airbag warning light remains on, the cent\
er airbag
sensor assembly has detected a malfunction code. (See page AB±30).
BO±8
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BODY General Information
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POWER WINDOW CONTROL
SYSTEM
Description
The Power Window System raises and lowers the window glass in each door usi\
ng electrical power. The compo-
nent parts of this system and their functions are described in the following\
table.
Parts NameFunction
Theft Deterrent and
Door Lock
Control ECUCurrent is sent to the power window main relay only when the ignition sw\
itch
is on or within a specified period after the ignition switch is turned o\
ff.
Power Window
Main RelayCurrent from the theft deterrent and door lock control ECU to the power
window main relay switches large current from the master switch ON and O\
FF.
Master SwitchThis switch turns current to each power window motor ON and OFF and
switches it. It also includes a circuit for ºOne Touch Power Windowº use of
the driver's window and a built±in window lock switch which controls the
operation of all power window switches.
Power Window
SwitchThis switch is installed on each door except on the driver's door. It is supplied
with current from the master siwtch and turns the current to the motor O\
N and
OFF and switches the current. This switch will not operate when the wind\
ow
lock switch inside the master switch is in the LOCK position.
Power Window
MotorThis motor moves the window regulator directly when current is supplied \
to it
from the master switch or power window switch. The motor has a built±\
in
circuit breaker.
Parts Location
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BODY ELECTRICAL SYSTEM Power Window Control SystemBE±147
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(c) Set the window lock switch to the lock position, checkthat all the passenger's power window switch
illuminations go out.
If operation is not as specified, replace the master switch.
(One Touch Power Window System/Current of Circuit)
Inspection using an ammeter.
(a) Disconnect the connector from the master switch.
(b) C onnect the positive (+) lead from the ammeter to
terminal 9 on the wire harness side connector and the
negative (±) lead to negative terminal of the battery.
(c) Connect the positive (+) lead from the battery to terminal
10 on the wire harness side connector.
(d) As the window goes down, check that the current flow is approximately 7 amperes.
(e) Check that the current increases approximately 14.5 amperes or more when the window stops going down.
HINT: The circuit breaker opens some 4±40 seconds after the
window stops going down, so that check must be made be-
fore the circuit breaker operates.
If the operation is as specified, replace the master switch.
Inspection using an ammeter with a current±measuring
probe.
(a) Remove the master switch with connector connected.
(b) Attach a current±measuring probe to terminal 4 of the
wire harness.
(c) Turn the ignition switch ON and set the power window switch in the down position.
(d) As the window goes down, check that the current flow
is approximately 7 amperes.
(e) Check that the current increases approximately 14.5 amperes or more when the window stops going down.
HINT: The circuit breaker opens some 4±40 seconds after the
window stops going down, so that check must be made be-
fore the circuit breaker operates.
If operation is as specified, replace the master switch.
BE±150
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BODY ELECTRICAL SYSTEM Power Window Control System
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(Switch Circuit)
Disconnect the connector from the master switch and inspect
the connector on the wire harness side as shown.
Check forTester connectionConditionSpecified value
Voltage9±GroundIgnition switch turned to ONBattery voltage
Continuity8±GroundConstantContinuity
If the circuit is not as specified, refer to BE±148 wiring dia-
gram and inspect the circuits connected to other parts.
(Power Window Switch)
REMOVAL AND INSTALLATION OF
POWER WINDOW SWITCH
(See page BO±33)
INSPECTION OF POWER WINDOW
SWITCH
INSPECT POWER WINDOW SWITCH
(Switch Continuity)
Inspect switch continuity between terminals.
Terminal
Switch
position
UP
OFF
DOWN
If continuity is not as specified, replace the switch.
(Switch Circuit)
Disconnect the connector from the switch and inspect the
connector on the wire harness side as shown.
Check forTester connectionConditionSpecified value
Voltage2±GroundIgnition switch ON andDOWNBattery positive voltagegg
master switch positionOFFNo voltage
3±GroundIgnition switch ONBattery positive voltage
4±GroundIgnition switch ON and UPBattery positive voltageg
master switch positionOFFNo voltage
If the circuit is not as specified, refer to BE±148 wiring dia-
gram and inspect the circuits connected to other parts.
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BODY ELECTRICAL SYSTEM Power WindowBE±151
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(Circuit)
(a) Disconnect the connector from the motor.
(b) Connect the connector to the master switch and powerwindow switch.
(c) Inspect the c onnector on the wire harness side as
shown.
Check forTester connectionConditionSpecified value
Voltage1±GroundIgnition switch ON andDOWNBattery positive voltagegIgnition switch ON and
master switch positionUP or OFFNo voltage
*Ignition switch ON andDOWNBatterypositive voltage* Ignition switch ON and
power window switch
DOWNBattery ositive voltage
power window switch
iti
UP or OFFNo voltagepositionUP or OFFNo voltage
2±GroundIgnition switch ON andUPBattery positive voltageIgnition switch ON and
master switch positionDOWN or OFFNo voltage
*Ignition switch ON andUPBatterypositive voltage* Ignition switch ON and
power window switch
UPBattery ositive voltage
power window switch
iti
DOWN or OFFNo voltagepositionDOWN or OFFNo voltage
*: Set the window lock switch to the unlock position.
If the circuit is not as specified, refer to BE±148 wiring dia-
gram and inspect the circuits connected to other parts.
(Theft Deterrent and Door Lock Control
ECU)
REMOVAL AND INSTALLATION OF
THEFT DETERRENT AND DOOR LOCK
CONTROL ECU
1. REMOVE THEFT DETERRENT AND DOOR LOCK CONTROL ECU
(a) Remove following parts.(See page BO±112 and 113)
w Instrument No. 1 Under Cover.
w Instrument No. 1 lower finish panel.
(b) Disconnect the connector and remove the ECU
2. INSTALL THEFT DETERRENT AND DOOR LOCK CONTROL ECU
For installation, follow the removal procedure in reverse.
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BODY ELECTRICAL SYSTEM Power Window Control SystemBE±155
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INSPECTION OF THEFT DETERRENT
AND DOOR LOCK CONTROL ECU
INSPECT THEFT DETERRENT AND DOOR LOCK CONTROL
ECU(Circuit)
(a) Inspect ECU Power Source Circuit.(See page BE±376)
(b) Inspect Actuator Power Source Circuit.
(See page BE±378)
(c) Inspect Ignition Switch Circuit. (See page BE±25)
(d) Inspect Door Open Detection Switch Circuit.
(See page BE±392)
If circuit is as specified, inspect ECU operation.
(Operation)
(a) With the connectors connected, shut all doors.
(b) Check that there is 10 V ~ 14 V between terminal B8 and
ground when the ignition switch is turned on.
(c) After turning the ignition switch off, check within 60 seconds that there is battery voltage between terminal
B8 and ground.
(d) Turn the ignition switch on then off, and check that there
is 10 V ~ 14 V between terminal B8 and ground when the
ignition is switched off.
(e) Open the front door within 60 seconds of turning the
ignition off and check that there is no voltage between
terminal B8 and ground.
(f) Close all the doors and turn the ignition switch on.
(g) When a front door is opened, check that there is battery voltage between terminal B8 and ground.
(h) Check that there is no voltage between terminal B8 and ground when the ignition switch is turned to off.
If operation is not as specified, replace the ECU.
BE±156
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BODY ELECTRICAL SYSTEM Power Window Control 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
numbers indicate the order of priority of the causes of trouble. Check each part in \
the order shown. If neces-
sary, replace the part.
See page
BE±4 ,21BE±4,21BE±4,20BE±4,20BE±156BE±152BE±149BE±151BE±152BE±26BE±392BE±4,20 ±±
Part
name
Trouble
AM1 FuseDOME FuseDOOR FusePOWER FuseTheft Deterrent and Door Lock Control ECUPower Window Main RelayPower Window Master SwitchPower Window SwitchPower Window MotorIgnition SwitchDoor Open Detection SwitchECU±IG FuseWire Harness
*1 Power window does not operate.1234
*2 Power window does not operate.35467218
ªOne Touch Power Window Systemº does
not operate.1
Only one window glass does not move.1234
ªWindow Lock Systemº does not operate1
ªWindow Lock Illuminationº does not light
up.1
Key±off power window does not operate124536
*1: Dook Lock does not operate.
*2: Dook Lock is normal.
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BODY ELECTRICAL SYSTEM Power Window Control SystemBE±157
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