I have a 2000 Buick Century that only has 70000 miles on it. I have an issue that when I drive the car for a while, the transmission will shift hard after stopping at a light or stop sign. It only does it through the first three gears. If I shut the car off and let it sit for a few minutes and start it back up, it shifts fine through all of the gears. I have not had the change to change the fluid and filter yet. The fluid looks clean and is always full. I have read that there has been a common problem with a pressure control solenoid in the transmission needing replaced to correct the hard shifting. Has anyone had this problem? I am not getting any kind of error codes from the PCM, so I am not sure. If anyone has had to do this, is it an expensive repair? Thanks.
Have the transnmission fluid and filter ever been changed? If not, I would try that first at a good independent shop that does not FLUSH. Flushing usually creates more problems.
I replaced the solenoids in our olds. The set is somewhere around $100. Labor was a couple hundred so not a great expense. Just schedule with a pan drop at the same time.
When the hard shifting is happening you probably do have transmission codes - but they won’t turn on the check engine light or show up with a typical, generic OBD-2 code scanner. You would need someone with a GM Tech II scanner or one with equivalent capabilities.
Depending on the codes, this kind of thing is a fairly common issue on those 4T65E’s. Sometimes it is related to the pressure control solenoid. And sometimes not. The place to start is with the codes, but the codes will probably not be present unless the car is acting up at the time. I’d find your best, locally owned/operated, non-chain transmission shop. Expect to pay an hour’s labor to have someone check it out and report back with the results if you like.
A bad tps can cause hard shifts in some GM transmissions. It should be cheap and easy to replace. Worth a try. Fixed mine.