1991 LEXUS SC400 Service Repair Manual

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Page 329 of 4087

LEXUS SC400 1991 Service Repair Manual
±MEMO±
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±89
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Page 330 of 4087

$LEXUS SC400 1991 Service Repair Manual DTC62, 63No. 1, No. 2 Solenoid Valve Circuit CIRCUIT DESCRIPTION Shifting from 1st to O/D is performed in combination with ON and OFF of the No. \ 1 and No. 2 solenoid valves controlled by ECM. If a$

DTC62, 63No. 1, No. 2 Solenoid Valve Circuit
CIRCUIT DESCRIPTION
Shifting from 1st to O/D is performed in combination with ON and OFF of the No. \
1 and No. 2 solenoid valves
controlled by ECM. If an open or short circuit occurs in either of the solenoid valves\
, the ECM controls the remain-
ing normal solenoid to allow the vehicle to be operated smoothly (Fail saf\
e function.
Fail Safe Function
If either of the solenoid valve circuits develops a short or an open, th\
e ECM turns the other solenoid ON and
OFF to shift to the gear positions shown in the table below. The ECM also turns the lock±up solenoid valve OFF
at the same time. If both solenoids malfunction, Hydraulic control cannot \
be performed electronically and must
be done manually.
Manual shifting as shown in the following table must be done. (In the case of \
a short circuit, the ECM stops send-
ing current to the short circuited solenoid).

Position

NORMAL

NO. 1 SOLENOID
MALFUNCTIONING

NO. 2 SOLENOID
MALFUNCTIONING

BOTH SOLENOIDS
MALFUNCTIONING
Position Solenoid valve Gear Solenoid valve Gear Solenoid valve Gear Gear when shift selectoris
No. 1 No. 2 Gear No. 1 No. 2 Gear No. 1 No. 2 Gear
Gear when shift selectorismanually operated
ON OFF 1st x ON 3rd ON x 1st O/D
D ON ON 2nd x ON 3rd OFF x O/D O/D
OFF ON 3rd x ON 3rd OFF x O/D O/D
OFF OFF O/D x OFF O/D OFF x O/D O/D
ON OFF 1st x ON 3rd ON x 1st 3rd
2 (S) ON ON 2nd x ON 3rd OFF x 3rd 3rd

()
OFFON3rdxON3rdOFFx3rd3rd
L
ON OFF 1st x OFF 1st ON x 1st 1st L ON ON 2nd x ON 2nd ON x 1st 1st
x: Malfunctions
Check the No. 1 solenoid when diagnostic trouble code 62 is output and check t\
he No. 2 solenoid when diagnos-
tic trouble code 63 is output.
DTC No.DTC Detecting ConditionTrouble Area
62, 63
Solenoid resistance of 8 or less is detected (*)
8 times or more when solenoid is energized.
Solenoid resist ance of 100 k or more is detected
(*) 8 times or more when solenoid is not energized. Solenoid valve.
Harness or connector between solenoid and
ECM.
ECM
(*) If the above failures are detected less than 8 times, the ECM memo\
rizes the malfunction code but the O/D
OFF indicator light doesn't blink. AT±90
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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Page 331 of 4087

LEXUS SC400 1991 Service Repair Manual
AT±66IN±33
WIRING DIAGRAM
DIAGNOSTIC CHARTDIAGNOSTIC CHART
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±91
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Page 332 of 4087

LEXUS SC400 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 be

Page 333 of 4087

LEXUS SC400 1991 Service Repair Manual
±MEMO±
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±93
WhereEverybodyKnowsYourName

Page 334 of 4087

LEXUS SC400 1991 Service Repair Manual
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 contr

Page 335 of 4087

Page 336 of 4087

LEXUS SC400 1991 Service Repair Manual
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

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