Question : Need Help on Grand Prix GTP Transmission

[MOTORHEAD86]

4T60 or 4T60-E?
Why would one GP have a 2nd gear start switch? does one transmission operate differently than the other.

John -Motorhead86

[gpse3400]

The 3.4 equipped Grand Prix's had a 2nd gear start switch, which back in the day was an early example of a type of traction control. All 3.4 automatic W bodies were mated to 4T60-E's.

[MOTORHEAD86]

I see. My '92 Has a switch, but my '91 Doesn't. Just a red LED in place of a switch. Plus, it won't shift into 1st gear or overdrive at all. Reason why I was asking is because I thought it had something to do with that switch. Now I realize I have a disconnected vacuum hose somewhere on the transmission. Just have to find it now.

[gpse3400]

You will always have first gear when stopped unless you have a bad shift soleniod. Since you are missing two gears I would say its that. A broken vacuum line will not prevent 1st gear.

[MOTORHEAD86]

Yes. Ive been checking out other forums, and they all say the same thing. Shift solenoids. Since Im doing a fluid and filter change, its best to ask before doing. Does the tranny need to be dropped to change the solenoids, or can it be done under the hood? Will the axle need to come off if I unbolt the valve body cover?

[gpse3400]

Its going to be a real pain in the ass. The best way to get at it, is support the car on jack stands and support the engine transmission either with a jack with the pad on wood or with a ane gine support frame, remove the strut, axle, disconnect the steering shaft from the rack, and drop the side of the frame, which also includes loosley unbolting the passenger side to allow the frame to swing. Remove the transmission mount bracket on the transmission and on the subframe. Then lower the transmission the rest of the way to get the side pan off, this job is hard and messy. I've done it too many times than I care to remember. To retain yor alignment you should remove it all from the top, and I dont think you can pull them all at once either. Dont forget to get a new transmission pan gasket and only buy internal solenoids and switches from GM. There is a total of 3 soleniods, shift soleniod A and B and the TCC, and 2 pressure switches. They arent too expensive at all. Clean up the side pan mating surfaces and back up your side pan bolts and nuts with red lock tight, and make the bolts only snug and go around them 3 times.