1991 grandprix transmission

kyledel · #1 11-13-2008, 07:03 PM

I have a 91 GP GTP 3.4L v6 and im gonna have to find a new tranny for it. I know it uses the 4T60-E but i also know the same tranny i got out of a 95 is wired diffrent and while it bolts onto the motor it doesnt shift on its own as the wiring is completely diffrent. Does anyone know from what years and models of cars i can get a tranny for my car?

tblake · #2 11-13-2008, 07:29 PM

Do you still have the old transmission?

Is it possible for you to remove the sidepan, exposing the valve body and tranny internal wireharness?

It might be possible to swap out the internal wire harnesses to get the right wiring. However the 95 might have an extra pcs. Not sure..... Might be worth a shot, might not, Its your decision, its a gamble.

kyledel · #3 11-13-2008, 07:31 PM

yea ive got the old one. is there anyway to know for sure if it will work? i dont wanna tear the one apart in the car if it wont work.

tblake · #4 11-13-2008, 07:31 PM

BTW, sorry I can't be of more help with the wire diagrams. I must have looked them over a bunch of time, and I just cant make sence out of them. They seem to be calling the components different names. I could tell you what to try, but I'd pretty much be taking a shot in the dark. Plus then you would have a tranny that wouln't shift, and a car with a cut and hacked up wire harness.

kyledel · #5 11-13-2008, 07:34 PM

well as of right now the wiring harness is hacked up beyond belief (the car has been destroyed by previous owners) and right now im driving it without the wiring harness plugged into the tranny and im just using the gear selector to shift. I only have 1st and 4th? gears but its getting me around for now. If you have an idea of how i can cut and splice the wires tell me and ill give it a shot. i dont really care how the wiring looks as im going to drive this car into the ground.

tblake · #6 11-13-2008, 07:35 PM

Quote:

Originally Posted by kyledel

yea ive got the old one. is there anyway to know for sure if it will work? i dont wanna tear the one apart in the car if it wont work.

I had the same issue with an older Buick (if I remember right). It was early 90's, and the junkyard sold us a tranny that bolted in, but we were lucky enough to notice the different wiring before we installed it. Once pulled apart, we just swapped the harnesses. Once is was in the car it seemed to work no problems. However after it was installed it was found to have a slipping clutch, it slipped hard in 2nd gear, so needless to say it came back out and a different one went back in.

Not sure if this would be a possible solution to your problem or not.

tblake · #7 11-13-2008, 07:37 PM

Quote:

Originally Posted by kyledel

well as of right now the wiring harness is hacked up beyond belief (the car has been destroyed by previous owners) and right now im driving it without the wiring harness plugged into the tranny and im just using the gear selector to shift. I only have 1st and 4th? gears but its getting me around for now. If you have an idea of how i can cut and splice the wires tell me and ill give it a shot. i dont really care how the wiring looks as im going to drive this car into the ground.

I will give the diagrams another thourough look and see what I can come up with. Do the wire colors on your car match the diagram colors for the 91 I gave you? Just curious.....

kyledel · #8 11-13-2008, 07:40 PM

yep they match

tblake · #9 11-13-2008, 07:42 PM

Do you have any sort of a small pigtail or connector off the newer tranny? If so, do this colors match up to the diagram I gave you of the 95 3.4 tranny?

tblake · #10 11-13-2008, 07:45 PM

Also just curious, did you swap over the VSS and the PRNDL switch from the 91 tranny to the 95 tranny? I think Rich might have ask that already. Sorry for being repetative.

kyledel · #11 11-13-2008, 07:49 PM

i have the pig tail and the colours also match the diagram so both sets of wiring match there diagrams

tblake · #12 11-13-2008, 07:53 PM

Sounds good. I'll check it out and report what I find a little later.

I just hope you dont get mad at me if I suggest something, and it turns out to not work. Not to mention the possibility of electrical shorts and damage to your shift solonoids or worse your PCM.

I'll let you know what I can figure out.....

tblake · #13 11-13-2008, 07:54 PM

ECM, not PCM, My Bad!

kyledel · #14 11-13-2008, 08:05 PM

Haha i wont get mad if it doesnt work and the chances of electrical shorts or ecm/solonoide damage is probably quite small i would imagine.

tblake · #15 11-13-2008, 08:20 PM

I just looked into it. You can cut and splice the wires for the shift solonoids, problem is going to be your old trans has 1st gear and 4th gear signal switches that the ECM uses for inputs. Your old trans TCC is also controlled by PCM for ON, and is turned off by brake switch input. On the 95, the tranny TCC solonoid is controlled by a ground signal from the PCM and gets constant B+. I'm pretty sure there is no easy cut and splice way of getting it to work unfortunatly. Only possible option would be to go inside and start swapping around internal components and by the time you go through all that work and the car still doesnt shift, you might as well have found a different tranny.

Have you considered sending in your 91 for reduild while you have the 95 installed and sort of drivable?

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