Auto Transmission Jerking

COZWV · November 12, 2002

I have a 2000 Chevy that has the all to familiar JERK/Slam when it changes gears.

This is a company truck and we have a 99 that also does the same thing.

I had it serviced and they changed the valve body? (I dont know exactly what because our shop foreman had the work done)

Well now its worse than it was. I drive 10-15 miles and it will start slamming when it shifts. If I pull over shut it off for a few minutes then it shifts good again for another 10-15 miles. :angry:

It seems like a pressure problem. The most noticable is when im at highway speed and accelerate to pass, It downshifts fine but when I let off of the gas thats when it slams.

Are there any other sites anyone knows of that may have some more info?

Thanks, COZWV

Cop_Dodger · November 12, 2002

There is a bullitin on the valvebody. From what I hear GM is on their third design to fix this problem. Something inside the transmission is causing excessive line pressure. It could be a blocked accumulator piston but that's highly unlikely. It could also be the pressure regulator, but that probabbly was replaced when the valve body was replaced. I can't think of anything else.

Cop_Dodger · November 16, 2002

I've been thinking about this problem. It could be the "adapt-shifts" program. This is a program that when the truck is new and you drive with a heavy foot it will shift harder then someone driving around moreconservativly. There are two ways I know of to clear the program. Easiest way is to leave the battery disconnected for a few hours. This should clear all the info. in the PCM. The other way is to bring it to your dealer and get them cleared. They use a diagnostic computer called a Tech 2 to clear the "adapt-shifts" program.