ect LEXUS SC300 1991 Service Repair Manual

OKNG
OKNG
INSPECTION PROCEDURE
1Check No. 1, No. 2 solenoid valves.
C
OK
P
C
P
OK
C
Electrical Check
1. Jack up the vehicle.
2. Remove oil pan.
3. Disconnect solenoid connector.
Measure resistance between solenoid connector and
body ground.
Resistance: 10 ± 16

Connect positive
lead to terminal of solenoid connec-
tor, negative  lead to solenoid body.
The solenoid makes an operating noise.
Mechanical Check
1. Remove the oil pan.
2. Remove the No. 1 and No. 2 solenoid valves.
1. Applying 490 kPa (5 kgf/cm
2, 71 psi) of compressed
air, check that the solenoid valves do not leak air.
2. When battery positive voltage is supplied to the so-
lenoid valves, check that the solenoid valves open.
Replace solenoid valve.
2Check harness and connector between ECM and solenoid (See page IN±33\
).
Repair or replace harness or connector.
Proceed to next circuit inspection shown on ma-
trix chart (See page AT±66). However, when diag.
trouble code 62 or 63 is displayed, check and re-
place ECM.
AT±92±
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DTC64No. 3 Solenoid Valve Circuit
(For Lock±up Control Pressure Modulation)
CIRCUIT DESCRIPTION
The No. 3 solenoid valve is provided for lock±up operations.
The lock±up operation pressure is controlled by the linear sole-
noid for smooth engagement.
The amount of current flow to the solenoid is controlled by the
duty ratio (See page AT±82) of ECM output signal. The higher
the duty ration becomes, the higher the lock±up hydraulic pres-
sure becomes during the lock±up operation. If the malfunction
occurs in this circuit and diagnostic trouble code 64 is stored in
memory, the O/D OFF indicator light does not blink.
DTC No.DTC Detecting ConditionTrouble Area
64
All conditions below are detected for 1 sec. or more.
2 trip detection logic*
(a) ECM outputs duty signal to No. 3 solenoid in 90%
or higher duty ration.
(b) Current to No. 3 solenoid: 450
100 mA or less.
 No. 3 solenoid valve
 Harness or connector between No. 3 sole-
noid valve and ECM.
 ECM
*: See page AT±62
Reference
 Waveform between terminals SLU± and E
1 when lock±up function is not operated.
Reference
 Waveform between terminals SLU± and E
1 when lock±up function is operated.
AT±94±
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OKNG
INSPECTION PROCEDURE
1Check No. 3 solenoid valve.
C
OK
P
C
OK
C
OK
C
OK
Check solenoid resistance
1. Jack up the vehicle.
2. Remove oil pan.
3. Disconnect solenoid connector.
Measure resistance between terminals 1 and 2 of sole-
noid connector.
Resistance: 3.5 ± 3.9

Check solenoid operation
Connect positive  lead with an 8 ± 10 W bulb to termi-
nal 1 of solenoid connector and negative  lead to ter-
minal 2, then check the movement of the valve.
Reference
Check solenoid operation
1. Prepare a variable power supply.
2. Connect positive  lead of the variable power sup-
ply to terminal 1 of solenoid connector and negative
 lead to terminal 2.
3. Check the movement of the valve when the voltage is gradually increased. (A current greater than 1 A
should not be supplied.)
As the voltage is increased, the valve should move
slowly in the direction.
4. Check the movement of the valve when the voltage is cut off.
The valve should return in the direction.
Replace No. 3 solenoid valve.
Go to step
.
AT±96±
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OKNG
2Check harness and connector between battery and No. 4 solenoid valve, No. 4 solenoid valve\
and ECM (See page IN±33).
Repair or replace harness or connector.
Proceed to next circuit inspection shown on ma-
trix chart (See page AT±66). However, when diag.
trouble code 64 is display, check and replace ECM.
±
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This sensor detects the rotation speed of the O/D input shaft from the
rotation of the O/D direct clutch drum.
Its construction is the same as that of the No. 2 vehicle speed sensor
(See page AT±86).
By comparing the O/D direct clutch speed signal and the No. 2 vehicle
speed sensor signal, ECM detects the shift timing of the gears and ap-
propriately controls the engine torque and hydraulic pressure in re-
sponse to various conditions, thus performing smooth gear shift.
DTC67O/D Direct Clutch Speed Sensor Circuit
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
67
All conditions below are detected for 4 secs. or more
2 trip detection logic*
(a) Gear position: 1st, 2nd and 3rd
(b) T/M input shaft rpm: 100 rmp or more
(c) T/M output shaft rpm: less than 300 rpm
(d) PNP: OFF (other than P or N position)

O/D direct clutch speed sensor.

Harness or connector between O/D direct
clutch speed sensor and ECM.

ECM
*: See page AT±62.
Reference

Wave form between terminals NCO
+ and NCO± during engine idling.
AT±98
±
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NGNG
OKNG
INSPECTION PROCEDURE
1Check resistance between terminals NCO+ and NCO± of ECM connector.
C
OK
PConnect the check harness A to the ECM (See EG sec-
tion).
Check resistance between terminals NCO
+ and NCO±
of ECM connector.
Resistance: 560 ± 680

Proceed to next circuit inspection shown on matrix chart
(See page AT±66). However, when diag. trouble code 67
is displayed, check and replace ECM.
2Check O/D direct clutch speed sensor.
C
OK
Hint
P
OK
C
Remove O/D direct clutch speed sensor from transmis-
sion (See page AT±17).
Measure resistance between terminals 1 and 2 of O/D
direct clutch speed sensor.
Resistance: 560 ± 680

Reference
Check the speed sensor function
Check voltage between terminals 1 and 2 of the speed
sensor when a magnet is put close to the front end of the
speed sensor then taken away quickly.
Voltage is generated intermittently.
The voltage generated is extremely low.
Replace O/D direct clutch speed sensor.
Check and repair harness and connector between
ECM and O/D direct clutch speed sensor (See
page IN±33).
AT±100±
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WIRING DIAGRAM
AT±66
IN±33
Throttle Position Sensor Circuit
CIRCUIT DESCRIPTION
The throttle position sensor detects the throttle valve opening angle and s\
ends signals to ECM.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
AT±102±
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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.
±
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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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The park/neutral position switch detects the shift lever
position and sends signals to ECM.The ECM receives
signals (R, PNP, 2 and L) from the park/neutral position
switch. When the signal is not sent to the ECM from the
park/neutral position switch, the ECM judges that the
shift lever is in the D position.
AT±66
IN±33
WIRING DIAGRAM
Park/neutral Position Switch Circuit
CIRCUIT DESCRIPTION
DIAGNOSTIC CHARTDIAGNOSTIC CHART
AT±106±
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