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.