drops back to 2nd

I wanted to know if there was anything else that would make a tranny not go into 3rd gear. Is there a fuse something or does it have to be a solinoid this is my 2nd tranny and this is the same reason I changed the last one

We need more info. year,engine,3spd or 4spd tranny SES light on?

Sorry about that its a 95 aurora 4.0. The car has 155k miles but its been well maintainedso it runs strong I dono what and I think its a 4sp. It shifts back down when u hit about 45 and keep your feet on the gas the reason imwondering if its a sensor is because this is the 2nd time and the same thing in both trannys

Thanks for the reply

I did a bunch of maintenance work on my car all at the same time. Changed the Throttle Position Sensor, cleaned the butterfly on the TB, Plugs, wires, PCV valve, EGR clean, and more. I had the same exact circumstances. The car would not shift into overdrive. My problem was that my TPS sensor was for a '96 and not a '95. The computer in turn bypassed the TPS and that shuts down the EGR. With the EGR shut down by the PCM, the transmision will not shift into Overdrive. Check your TPS and EGR. It is not normal for the tranny not to shift into OD because of a tranny problem. I think that OD is a lot different than the 'planetary gears' and not reliant on shift solinieds. I would say check your codes, but like my OBD1 '95 it costs almost $100. Good luck, hopefully it is a minor problem.

-edit.

I think I misread the above. This is still good info though so I will leave it.

I also have a '95 Oldsmobile Aurora that drops back down to second gear, only mine creates problems once it reaches 40mph. When the vehicle is cold it runs beautifully, but once it has a chance to warm up it slips back down to second gear. I have replaced the solenoids and transmission gasket, but that didn't fix the problem. Didn't think about the TPS sensor. I'm hoping this could be a potential solution. It is a V-8 4.0 Liter engine. Anyone have any other thoughts??