I have a 2000 Monte Carlo LS with 117,000 miles and I'm looking for some info about the problem I'm having.

Once the car has been running for a while, the transmission will start shifting hard between all the gears, and once it starts doing that there is a constant whining noise from the trans even if it is in neutral or park. Even in park the whining follows the speed of the engine. If I shut the car off for just 10 or 20 seconds (sometimes it could even take a few minutes) the sound will be gone and the trans will shift normally for a while until it starts doing it again. Also the torque converter is not completely locked. If I give it some gas I can get it to unlock and it still shifts hard.

After looking around some forums for simple suggestions, I double checked the 20-way connector to the trans to make sure it was clean and in good shape. I also scanned and returned no codes.
I'd really like to try and pinpoint the problem because I know any shop around here will really push for me to just get the whole thing rebuilt.
I dont think it's necessary to rebuild it though. When it shifts normally, it's flawless. The fluid is red and doesnt smell burnt. A lot of stuff I've read so far points to the PCS for this type of problem.

Any thoughts?

from what i know when you have malfunctions depending on the type of problem in the tranny it will automatically kick to full pressure shifts. causing your hard shifting. the whining noise i am unsure i have a 4T60E tranny in another vehicle and i have the same whine but its my junker car and i dont care. it could also be your planetary gears giving you that whining sound.

what is the tranny in that 65E or a 60E

Don't drive it withthe harsh heavy shifts. What is happening is the PCM is commanding full line pressure to the tranmission and your getting the harsh shifts. When you shut it off, the PCM resets and your good until it happens again. If you drive it with high line pressure, you'll destroy your transmission. Common on these transmissions (4T65E) is the the PWM valve goes bad and causes this. This may not be your case, but from what you describe and what it sounds like, thats sounds like its your problem.

The whining noise is the tranny oil pump being overworked at full line pressure.

Thanks!

I would just like to add. It is the high line thats making the whine noise. Surprised someone can't get a code out of it. When limp mode is commanded by the transmission module(harsh shifts and no 4th and lock-up) there has to be a code stored somewhere in there. Some scanners will not pull all codes or some are in memory/freeze frame and such. Someone needs to get deeper into the module data and look at the adaptives (TAPS) and shift error timing to pinpoint the failure. PCS is the common. But we are finding alot of valvebody problems with worn bores...