4th transmission

[RM686]

1999 GRAND PRIX GT 165,000 miles. I just had the 4th transmission put in at a cost of $2800.00 3 year warranty. The car was shifting very hard and a whining noise could be heard upon acceleration. I went to a rebuild transmission shop and my general mechanic. The rebuild guy wanted to take it apart and see what was needed replacing and my mechanic suggested a remanufactured trans. I went with the remanufactured one and after the install the mechanic called me and said the transmission was still shifting hard. He then did some further diagnostics and found a wiring problem from the PMC to the transmission. By the way I still hear the whining noise. I may have just not noticed it before the transmission started shifting hard.
The reason for this post is that upon some Google research a problem with the wiring between the PMC and the transmission is common with the Grand Prixes, resulting in hard shifting. I believe I just threw $2800.00 away.
No codes showed up on the check engine light and neither mechanic did a scan for stored codes. A word of advice if you are experiencing hard shifts with your transmission go to an electrical shop first with good scanning equipment first before going to a transmission or mechanic. I don't believe my mechanic was trying to rip me off but was just lazy and did not do due diligence. Kelleys Blue Book says my trade in value is $1000.00 and retail sale price is $2000.00. I have way too much money now invested in this car to ever sell it. New air compressor $800.00 3 months ago plus new tires, wheels and struts and springs . I will just drive it into the ground. Boy do I feel stupid.
Just thought someone out there could benefit from my experience.

 

[hensleya1]

I paid ~150 for my last a/c compressor (although admittedly not including freon). And for $2800 you could have a performance trans from TEP built and likely installed with enough left for a kegger afterwards. You got had from here all the way to pacoima.

That said, I once had a car that had a bad turbine speed sensor, p0717, that caused fourth gear to have a mind of its own (it would work sometimes).

When the trans was heated up (trans temp above ~200 or so), it would start popping into gear. It was a bad PCS solenoid that acted funny when the trans got hot so the PCM would command max line pressure. The band aid solution for that was just to tune for a lower operating temperature (~185 degrees and the trans never acted up again).

 

[NotEnoughGPs]

Having driven GP's for 15 years now, I seen my share of transaxle problems.
You state that it is important to find the right shop/mechanic to do repairs on your GP. I would always be careful trusting repairs to a shop/mechanic who is strictly looking for profit in repairing your car. I have horror stories to tell about how I spent thousands of dollars since 1999 to have work done on the GP's I have owned.
I would say to keep writing to this forum each and every time you have an issue with the GP. Tons of help on here. I understand you may be in a position that you cannot do the work on your car yourself, so that makes it difficult. At least, by doing searches on GPF and asking questions, you can keep a close eye on a shop as they do work on your car. Always question them in everything they do.
What hensleya1 mentioned is so true: for $2800, you could have gotten a high performance trans that you would never have trouble with again, and had money left over.
As for the issue with the hard shifting, I had that happen to 2 of the GP's I owned, and in each case, I had the PCM tuned so that the trans line temps were lower. I have not had they hard shifting issue since.