ignition LEXUS SC300 1991 Service Manual PDF

(1) Connect negative (±) terminal cable to battery.
(2) Clear malfunction code 41 stored in memory(See page AB±32).
Check center airbag sensor assembly.
Replace center airbag sensor assembly.
(1) Turn ignition switch LOCK, and wait at least 2
seconds.
(2) Turn ignition switch ACC or ON, and wait at least 20 seconds.
(3) Using SST, connect terminals Tc and E
1 of
TDCL.
SST 09843±18020
(4) Check diagnostic code.
Codes other than code 13 may be output at this
time, but this is not relevant to this check.
Diagnostic code 13 is not output.
(1) Turn ignition switch LOCK.
(2) Disconnect battery negative (±) terminal cable, and wait at least 2 seconds.
(3) Connect steering wheel pad (squib) connector.
(4) Connect negative (±) terminal cable to battery.
(5) Clear malfunction code 41 stored in memory
(See page AB±32).
Check squib.
Replace steering wheel pad.
Codes other than code 13 may be output at this
time, but this is not relevant to this check.
Diagnostic code 13 is not output.
(1) Turn ignition switch LOCK, and wait at least 2
seconds.
(2) Turn ignition switch ACC or ON, and wait at least 20 seconds.
(3) Using SST, connect terminals Tc and E
1 of
TDCL.
SST 09843±18020
(4) Check diagnostic code.
From the results of the above inspection, the malfunctioning part can now be\
considered normal.
To make sure of this, use the simulation method to check. AB±57
SRS AIRBAG
± Troubleshooting
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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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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
±
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CHECK TERMINAL TT OUTPUT
VOLTAGE
AT00R±01
When a voltmeter is connected to the DLC1, the following
items can be checked.
1. Throttle position sensor signal
2. Brake signal
3. Shift position signal
1. VOLTMETER CONNECTION Connect the positive (+) probe of the voltmeter to terminal T
T
and the negative (±) probe to terminal E1 of the DLC2.
HINT: If a voltmeter with small internal resistance is used, the
correct voltage will not be indicated, so use a voltmeter with
an internal resistance of at least 10 k
.
2. TURN IGNITION SWITCH TO ON (DO NOT START THE
ENGINE)
3. CHECK THROTTLE POSITION SENSOR SIGNAL Check if the voltage changes from approximately 0 V to
approximately 8 V when the accelerator pedal is gradually
depressed from the fully closed position.
4. CHECK BRAKE SIGNAL (LOCK±UP CUT SIGNAL)
(a) Open the throttle valve fully to apply approximately 8 V to terminal T
T.
(b) In this condition, check terminal T
T voltage when the brake
pedal is depressed and released.
TT terminal voltage:
0 V (When brake pedal is depressed)
8 V (When brake pedal is released)
5. START ENGINE
6. CHECK SHIFT POSITION SIGNAL (VEHICLE SPEED ABOVE 60 KM/H OR 37 MPH)
Check up±shifting together with terminal T
T voltage.
HINT: Check for light shocks from up±shifting and for
changes in the tachometer.
 Gear Position Terminal TT output voltage 1st GearBelow 0.5 V 

2nd Gear1.5 ~
2 6 V
 3rd Gear3.5 ~ 4.6 V
 3rd Lock±up4.5 ~ 5.9 V
 O/D5.5 ~ 6.9 V
 O/D Lock±up6.5 ~ 7.9 V
If terminal TT output voltage check cannot be performed, per-
form the check of terminal T
T circuit on page AT±120.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±39
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OKNG
OKNG
INSPECTION PROCEDURE
1Check operation of speedometer.
Drive the vehicle and check if the operation of the speedometer in the c\
ombination meter is normal.
The No. 1 vehicle speed sensor is operating normally if the speedometer dis\
play is normal.C
Hint
Check speedometer circuit. See combination meter
troubleshooting on BE section.
2Check voltage between terminal SPD of ECM connector and body ground.
C
OK
P3. Connect the check harness A to the ECM (See EG section.)
4. Shift the shift lever to N position.
5. Jack up one of the rear wheels.
6. Turn ignition switch ON.
Measure voltage between terminal SPD of ECM con-
nector and body ground when he rear wheel is turned
slowly.
Voltage is generated intermittently.
Check speedometer circuit. See combination meter
troubleshooting on BE section.
Proceed to next circuit inspection shown on ma-
trix chart (See page AT±66).
However, when diag. trouble code 42 is displayed,
check and replace ECM.
AT±80±
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OKNG
OKNG
OKNG
INSPECTION PROCEDURE
1Main throttle position signal check.
C
OK
Hint
PTurn ignition switch ON (Do not start the engine).
Check voltage at the terminal T
T of the DLC2 while grad-
ually depressing the accelerator pedal from the fully
closed position to the fully opened position.
Voltage changes from 0 V to 8 V by stages.
Do not depress the brake pedal during this test. The
voltage will stay at 0 V if depressed.
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check throttle position sensor.
See engine troubleshooting section in EG section.
Replace throttle position sensor.
3Check harness and connector between ECM and throttle position sensor (S\
ee page IN±33).
Repair or replace harness or connector.
Check and replace ECM.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±103
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OKNG
OKNG
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal KD of ECM connector and body ground.
C
OK
P1. Connect the check harness A to the ECM (See EGsection).
2. Turn ignition switch ON (Do not start the engine.)
Measure voltage between terminal KD of ECM connec-
tor and body ground when accel. pedal is fully de-
pressed or not.
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check kick±down switch.
C
OK
1. Disconnect dick±down switch connector. (See page AT±18)
2. Measure resistance between terminals 1 and 2 of kick±down switch connector when kick±down
switch is ON and OFF
Replace kick±down switch.
3Check harness and connector between ECM and kick±down switch, kick±down\
switch and
body ground (See page IN±33).
Repair or replace harness or connector.
Check and replace ECM
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±105
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OKNG
OKNG
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal R, PNP, 2, L of ECM connector and body ground.
C
OK
P1. Connect the check harness A to the ECM (See EGsection).
2. Turn ignition switch ON.
Measure voltage between terminals R, PNP, 2, L of
ECM connector and body ground when the shift lever is
moved to the following positions.
*: The voltage will drop slightly due to lighting up of the
back up light.
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check park/neutral position switch.
C
P1. Jack up the vehicle.
2. Remove park/neutral position switch (See page AT±18).
Check continuity between each terminal shown below
when the shift lever is moved to each position.
Replace park/neutral position switch.
3Check harness and connector between ECM and park/neutral position switch, park\
/neutral
position switch and battery (See page IN±33).
Repair or replace harness and connector.
Check and replace ECM.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±107
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OKNG
OKNG
OKNG
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.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±109
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OKNG
OKNG
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal P of ECM connector and body ground.
C
OK
Hint
P1. Connect the check harness A to the ECM (See EGsection).
2. Turn ignition switch ON.
Measure voltage between terminal P of ECM connector
and body ground when the pattern select switch is set
to the PWR (POWER) position and NORM (NORMAL)
position.
The ECM uses the normal pattern signal if the power
signal is not input.
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check pattern select switch.
C
OK
PDisconnect pattern select switch connector. (See BO
section).
Measure resistance between terminals 1 and 2 of pat-
tern select switch connector when the select switch is
set to PWR and NORM positions.
Replace pattern select switch.
3Check harness and connector between ECM and pattern select switch, patte\
rn select switch
and battery (See page IN±33).
Repair or replace harness or connector.
Check and replace ECM.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±111
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