2002 4T60E slam shifting

After warm up, my 2002 Grand Prix starts slam shifting through all the gears, including torque converter lock up. It is shifting at the right time as far as speed/throttle position but it just slams into each gear. If I stop the car and shut off the engine and wait a moment, then restart, it will shift smoothly through all the gears. Then the next time I slow down and go through the gears again, it's back to slam shifting. This is the 4T60E tranny with no modulator. The modulator was not used on 2000 and newer, according to Haynes.
Thanks for any ideas.

To start the transaxle is a 4T65E which is different from the 4T60E. No vacuum modulator and some other internal differences. Line pressure on the 4T65E is controlled by a pressure control solenoid (PCS) and it sounds like you have an issue with it. Get it scanned and see if a P1811 DTC is stored.

:confused:

BTW - The Haynes is incorrect and you should trash it. The 4T65E was first used in the second half of the 1998 production year. :2cents:

Haynes manual is just using a generic production change date. I believe the last 4T60E was produced in 99 after that date the 4T60E was no longer in production

Haynes manual is just using a generic production change date. I believe the last 4T60E was produced in 99 after that date the 4T60E was no longer in production

We are not talking general production info but info specific to the Pontiac Grand Prix which is where manuals such as Haynes fail. :thumbsdow

Actually the 4T65E was first used in 1997 as the 4T65 HD version in GTP models, GM RPO Code MN7. :wink:

The 4T65E RPO code is M15 for Grand Prixs so all the owner has to do is look at the SPID label located under the trunk lid.

I did find the M15 on the SPID. By getting it "scanned" do you mean the OBD II scan? I have an OBD II scanner and it showed no codes. Thanks much for the responses. bstrom1953

I order to be able to get the DTC codes you can try transmission shops, they should have the proper code scanner. The general code scanners that are cheap will not pull the ABS, transmission, or AC DTC. The cost of the scanner if you were to buy one, you are looking at at least 5K.

Sounds like a good candidate for Bob's trans fix.

Sounds like a good candidate for Bob's trans fix.

Possibly Tim. The thread is just sitting and waiting to be read at our Tips & Maintenance subforum. :dunno:

http://www.automotiveforums.com/vbulletin/showthread.php?t=920671