Need Help diagnosing tranny problem.

**trbsht** · 01-29-2009

I am new to this board and would like to say hello and also that any help with my particular problem is greatly appreciated.

My Grand Prix GTP has 233,000 miles on it and up till today I bragged to everyone how nice it ran.
I went on a 2000 mile round trip with it just this past week 800 miles one way, and not all in one day.
I got home last night , parked my car and went to bed. Then I got up this morning and drove 15 miles went back home and parked it. Everything just fine.
Then I need to go somewhere and I start it again put it in reverse and pull out but then I put it into drive and NOTHING all it does is rev like it's in nuetral, also does this same thing in 3 but in 2 and 1st its just fine drives like a champ of course I cannot drive to fast or even really go anywhere now.

What could have happened while it was parked????

Also my trip was to the tri states is and I drove through the ice storm you guys see on the news alot of ice hit the underside of the car.
Checked fluid and filter is 6 months old.

I have a few leads here they are.

Shift Solenoid went bad?
Electrical problem to Shift Solenoid?
Or Shift Solenoid fuse is blown?

Any help is greatly appreciated.
Thank You

**Trannyman95** · 01-30-2009

Not having forward range in D or 3 sounds like a broken forward band, but that wont effect reverse operation. The fact that you lost it all at the same time sounds like you likely have a blown channel plate gasket. Some diagnostic time with a pressure gauge and scan tool to control line pressure may reveal what the problem is but otherwise you are at the mercy of having to tear the trans half way apart to investigate. There is not much you can do with these transmissions without dropping them down and removing the side cover

**trbsht** · 01-31-2009

Thank You Trannyman.

I turned the car on today and let it run for 20 minutes. Then I shifted slowly through the gears Reverse works fine still and so does 1st and 2nd gear. Third gear and drive still do nothing.

Maybe this can help diagnose the problem. When I'm in reverse and when I put it in neutral the headlights and dashlights get dimmer and then when I move it to drive the lights come back to full brightness and the engine revs up to about 1000 rpms then settles back down, it does not do this from drive to 3rd gear.
Could this be electrical?

**Trannyman95** · 02-02-2009

The next thing you can try is to drive the car by manually shifting 1-2-3-4. Now that you mention reverse working that for the most part rules out the channel plate gasket being a #1 suspect. If you can get all 4 forward speeds by manually shifting then I would definately point at the forward band being broken. This can happen any time out of the blue for no rhyme or reason. If it is in fact broken you can verify this by removing the lower pan and looking up into a windowed out section in the trans case just past the narrow end of the filter. Straight up in this area you will see where the forward band sits and there is an apply pin sticking in from the back side of the case. You will either find a broken piece of band laying in the pan in this area or you will see the band is broken and still in place. If the band is broken it means a complete overhaul as the band is literally one of the last parts to come out of the case.

**pacothetaco** · 02-05-2009

could this also be a broken vac line? im experiencing the same problems except it wont go in reverse it does the same neutral rev. but if i let it sit for say 4 minutes off and then try it again it, reverse and forward will work for like maybe 10-ish minutes and only in low gears. just after this winter storm but i noticed behind my battery there was a vac line completely anihilated im not sure if thats even relavent to the problem.

thanks

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