Automatic Trans Only 2nd and 3rd gear when warm.

[habitatguy187]

So I picked up a 1g auto car that I'm planning to flip, but it has one problem I want to get figured out before I sell it.

After the car gets good and warmed up it tries to stay in 3rd gear and 3rd gear only unless you manual downshift it into second. If you put it in first it will only go to second, and often it won't go into overdrive once it's doing this. It's like it just gets stuck in 3rd.

Trans fluid is full and looks decent, when the car's cold it shifts through all gears smoothly. Any ideas/suggestions?

 

[las_vegaslazer]

I had the very same problem. I had a bad tcu. I swapped 3 trannys and had the same thing so the only thing left was the tcu. Changed the tcu and it has been running great for the last month.

http://www.dsmtuners.com/forums/automatic-tranny/351882-tranny-poblem-1g-awd.html