1991 LEXUS SC400 ignition

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±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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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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OKNG
OKNG
OKNG
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±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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NGOK
NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal OD1of 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 terminal OD1 of ECM con-
nector and body ground.
Voltage: 4 ± 6 V
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check voltage between terminal OD of cruise control ECU harness side con\
nector and body
ground.
C
OK
P1. Disconnect cruise control ECU connector.
2. Turn ignition switch ON.
Measure voltage between terminal OD of cruise control
ECU harness side connector and body ground.
Voltage: 4 ± 6± V
Check and replace cruise control ECU.
3Check harness or connector between cruise control ECU and ECM (See page\
IN±33).
Repair or replace harness or connector.
Check and replace ECM.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±117
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