check engine light comes on randomly and transmission goes to high gear instantly. light will go out randomly and transmission starts working instantly.

 

What engine type, V6 or 4 cylinder?

Describe the situation when this happens, as in MPH, accelerating, steady speed, etc.

What do you mean going into high gear?

Does the transmission actually shift gears or does the RPM just rise approx 300 rpm?

 

Sorry its a 4cyl. it does it at random time. I have drove the car doing fine and turned the car off and when I restarted the car the light would be on and when you put the car in drive it tries to start in high gear. I can manually put the car in low and it will go and i can shift up to drive but i can not take off. then randonly the light will go off and the car will be fine. when the check engine light comes on the engine will also idle rough.
Thanks for any help.

 

The transmission gear selection, shifting and torque converter lock up are normally electrically controlled.

The driver can override much of this and operate the trans manually if the electronic system fails or if wanting to keep the trans in a certain gear, turn off overdrive, etc.

To operate the trans electronically the gear shift valve body incorporates three 12 volt electric powered solenoids, one for each gear. The trans has an addition electric solenoid that when activated causes the torque converter to lock up.

The engine computer controls these solenoids based on MPH, RPM, throttle position, etc. and selects the appropriate solenoid to turn on to have the trans in the right gear.

There is a switch on the gear shift level then when out turns the O/D solenoid off and prevents lockup. The O/D light on the dash will illuminate when the O/D system is off (switch is in out position).

If the electric control system fails to perform as the computer expects, the computer is programmed to go into one of many default modes depending on how many systems are involved in the failure.

The check engine light may or many not come on for a trans code. Thus wonder if it is trans issue or just lack of engine power. However you being able to shift manually indicates a trans issue.

If all trans solenoids fail, the trans goes into a default high gear mode. The result is the car is now stuck in high gear which makes accelerating difficult.

Note: Prior to fixing the problem when the issue occurs use the manual gear shift as you do now when the check light is on.

The trans could also be stuck in O/D lockup, this is when the torque converter is locked. The converter is combination clutch and torque multiplier. This allows the trans load to be taken off the engine at coast and idle, and provide extra torque for moving from a stop.

If the converter locks up at the wrong time, the result will be extra load on the engine and slow acceleration. The converter if not turned off manually, will lockup after approx 40 mph when engine warm then unlock as the car slows down to under this speed, hard acceleration, etc.

The 94, 4-cylinder does not have ODB-II to allow reading code via a code reader. It does have built-in diagnostic system which can check for trouble codes and "read" them out.

Reading out engine and trans codes requires slightly different procedures.

To do either or both, look under the hood for a small plastic box labeled "Diagnostic" perhaps on the drivers or passengers strut tower.

Inside the box are electrical terminals. To read out engine codes find the T1 and E1 terminals.

Turn ign switch on.
Connect the T1 and E1 terminals with electrical wire or a bent paper clip.
Watch the check engine light on dash.
If codes are stored the light will flash out a two number code one number at time.
Example, 4 flashes, pause, 2 flashes, longer pause = code 42.
If more then one code is stored, codes will readout from lowest to highest. When all codes are read, they will repeat.
If no codes are stored the light will flash at a steady rate.
Once done reading codes, disconnect terminals and turn off ign key.

To read out trans codes find the E1 and TE1 terminals inside the same box.
Turn on ign key.
Check if O/D light on dash works by shifting the switch on the gear shift out, this should turn the light on.
If light works, push the switch back in to turn off light.
Connect E1 and TE1 terminals.
The OD light will now function the same way the check engine light did when checking engine codes with codes outputted the same way. If no codes are stored the light will flash at steady rate.
When done reading codes, disconnect terminals and turn off ign key.

If you find any codes post back or do an internet search on "Camry" and the code number(s). If more then one code, search one number at time. Each code will refer to a specific problem.

 

Update: changed the ecm and the camry is doing good. Thanks for the info.