After driving at a constant speed for awhile on the highway, or alot of city miles, I notice that when my transmission shifts gears, it gives a hard jerk. If I stop, turn the car off, let it sit for a bit, then it will go away. Is this due to overheating? Is the tranny going out? The fluid level is fine. I looked up the old car report and there was a sun gear replaced by the previous owner. Any thoughts?

That sounds like a solenoid that controls tranny shifts. Mine did the same thing and it took forever for the techs to figure it out. (This is before BC for me )I wish I could remember what the part is exactly... I don't have my papers on the car with me. It was under warranty for me and it was very expensive as I recall. Hundreds of dollars. Sorry .
But yes, if I shut the car off for about 20 secs to a minute, then it would run fine for a while... then jerk! I read on BC about it and you should try to get it fixed soon. Damage not likely in the short term, but don't let it go.

Good luck!

Doug

As fdh01bonneville mentioned, the most common cause is the pressure control solenoid. That requires the removal the the transmission side cover to service. If you haven't changed the filter and fluid lately, start there first.

that is exactly what mine is doing! i'm glad I'm not the only one now

Would this be something someone with decent mechanical knowledge and the proper tools could do themselves? I have heard this a is a common problem and with 70k miles on my car I would not put it out of the realm of possibility sometime in the future.

http://www.bonnevilleclub.com/forum/...ntrol+solenoid


Here'* a link to a thread concerning the Pressure Control Solenoid. I had the same symptoms with it jerking after warming up. To be sure you'll need to have a scan with a TECH II, which will likely require a trip to Pontiac/GM. Costly repair, but if your going to keep the car for a while I would suggest you get it taken care of sooner rather than later. Good Luck.

FYI, they fixed this problem on the 2003 and up model years. So '97-'02 got the stupid solenoid which costs $700+ to get replaced at a dealer. (I didn't have it done but I will just replace the whole transmission at some point).

I have a similar jerking problem. Sometimes maybe 20-13% of the time I will be driving at highway speed and when I lightly press the gas and let off it jerks like its banging in and out of gear. And two times over the past two weeks I think the tranny has slipped and then kinda banged into gear. I am under warranty for two more weeks and the shop says it tested the tranny and no problems. How should they check for this pressure silenoid? thnks

I have changed the filter and fluid.

If they're a good shop, they should access to the GM technical service bulletins. Have them check them out.

Just had my pressure control solenoid replaced today at the dealership. Lucky for me I have a powertrain warranty and it only cost me $50. It would have been $551.77 without the warranty.