Lexus SC300 / Lexus SC400. Service manual - part 84

–MEMO–

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A304E (1UZ–FE) AUTOMATIC TRANSMISSION

TROUBLESHOOTING

AT–93

DTC

64

No. 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 Condition

Trouble 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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A304E (1UZ–FE) AUTOMATIC TRANSMISSION

TROUBLESHOOTING

AT–66

IN–33

WIRING DIAGRAM

DIAGNOSTIC CHART

DIAGNOSTIC CHART

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A304E (1UZ–FE) AUTOMATIC TRANSMISSION

TROUBLESHOOTING

AT–95

OK

NG

INSPECTION PROCEDURE

1

Check 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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A304E (1UZ–FE) AUTOMATIC TRANSMISSION

TROUBLESHOOTING