tranny frequent downshift/upshift

[madbomber08]

I have an '89 Camry 4cyl auto. My parents bought the car as a demonstrator in 1990. It has 200,000 miles on it but has had a problem with the transmission ever since 2004. When you are cruising along at highway speeds (doesn't really matter how fast you are going i guess) the transmission will shift from o/d to 3rd and then 3rd to o/d again. The gas pedal needs no movement at all and the tranny will do this on its own. Sometimes it will shift down to 3rd and stay there for the whole trip. Then other times it will shift into o/d with no problems at all. It is an intermittent problem that is probably hard to find, as we have had tranny shops look at it and it still is bad. We still drive it everyday just not at highway speeds or we would piss a lot of people off by going only 45 or 50 mph. Any help or experience on this issue would be appreciated. Thanks

[270+Camry]

transmission solenoid maybe? I know on some cars (not the camry, I wouldnt even know where to find them on a camry) I've been able to take them off and clean them with brake cleaner. Also check your TCM to see if it has a code. I found this page that applies for the 87 camry about the TCM codes, I dont know if the codes are the same through 89, hope it helps. hopefully im way off and it's something really simple to fix. here's the page http://autorepair.about.com/library/...bl306a-lib.htm

[zythr]

If you have not done so, also check your thermostat. The tranny shifting is dependent on the ECU seeing if the engine is warm or cold.

[Camry_rider]

When was the last time you changed the fluid and filter?

My Es250 was having some trouble shifting when cold, and when it was warm it shifted harsh and would slip in and out of gears.

I changed the fluid and filter and it all cleared up, super smooth, crisp shifts, but after years of driving only manual cars I forgot about the tranny cooler in the radiator and now I need to do it all over again.

I would suggest inspecting your fluid. If it not red, change it and the filter, clean the pan out, MAKE SURE YOU GET A NEW GASKET!!!! See if that clears it up, drive it for a few hundred miles and change just the fluid again.

ALSO, give this manual a read. Make sure you go through every page of it. Im sure there will be something in it to help you diagnose this problem. Good luck to you.
http://camrystuff.com/manuals/Gen2/A..._Transaxle.pdf

[Doctor J]

To camry_rider: I used to have same car like in your signature but 79 not 81 and white 5-speed
To madbomber08: if your car has A140l NOT A140e tranny, there will be no codes.
In this case:
Make sure your fluid level is good, if it is good but problem persists,
On the top of coolant boss between the upper radiator hose and cylinder head locate single wire sensor in the middle facing up (looking similar to the fan switch on the thermostat housing), unplug it's connector and take car for a ride. If problem is gone, change this switch or you can drive like this, with switch disconnected, but push the o/d off button in for first few minutes of driving.