1991 Lexus LS 400 Improper Shifting

  • 1991 LEXUS LS 400
  • V8
  • 2WD
  • 157,000 MILES
My transmission will shift perfect when you first start off in it the car. Once it gets hot, transmission will skip gears. It will go from first gear to high and on the road the overdrive light will start flashing. Then sometimes it will shift fine again for a minute and start back with the same thing. Can someone shed some light on what the problem may be.
Do you
have the same problem?
Tuesday, August 17th, 2010 AT 10:44 AM

1 Reply

Hi sdavis100,

An error has been detected in the transmission control system and you need to retrieve the trouble code to understand what could be wrong.


1. Turn ignition on. DO NOT start engine. Press OD switch to the ON position. Fault codes can only be retrieved with OD switch in ON position. If OD switch is in OFF position, OD OFF light will be on continuously and will not blink fault codes.

2. Install jumper wire between terminals TE1 and E1 of Total Diagnostic Communication Link (TDCL) or check connector. The TDCL is located behind driver's side of instrument panel. Check connector is located on top left front corner of engine. See Fig. 2 .


3. Note number of blinks from OD OFF light on instrument panel. If normal system operation exists, OD OFF light will blink 2 times per second. See Fig. 3 .

4. If no fault codes are set, turn ignition off. Remove jumper wire. Perform symptom diagnosis. If fault code is set, OD OFF light will remain off for 4 seconds. After 4 seconds, OD OFF light will blink once every half second, indicating first digit of fault code.

5. After a pause of 1.5 seconds, OD OFF light will blink once every half second, indicating second digit of fault code. See Fig. 3 . If more than one fault code exists, next fault code will be displayed after a pause of 2.5 seconds.

6. If more than one fault code is set, smaller number fault code will be displayed first. Fault codes will repeat display sequence. To identify fault code, see
FAULT CODE IDENTIFICATION table. Perform appropriate fault code diagnosis. After repairing vehicle, clear fault codes.

Fault Code = Circuit Malfunction
42 = No. 1 Speed Sensor Circuit
46 = No. 4 Solenoid Circuit
61 = No. 2 Speed Sensor Circuit
62 = No. 1 Solenoid Circuit
63 = No. 2 Solenoid Circuit
64 = No. 3 Solenoid Circuit
67 = OD Direct Clutch Speed Sensor Circuit
68 = Kickdown Switch Circuit

The ECT ECU will not blink OD OFF light to warn driver if fault code 64 and 68 are set.


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Sunday, August 22nd, 2010 AT 4:08 AM

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