I believe you have a 4T60E transmission. A 96-99 GH with FSM will have to research that code and supply information. The fact that the gear selector isn't indicating intended selection is a new problem & could be why the DTC P1870 code is set. How did you discover the gear selector/indicator misalignment? The fix for that could be a simple cable adjustment.

i just checked trans fluid after i let it warm up and went thru the gears and the fluid is good but i noticed there are a 2 or 3 bubbles on the dipstick. I think this means the fluid should be flushed and filter. I disconnected the battery to get the code to disappear but it wouldnt go away. I hope a flush will fix this cause i dont want to spend money on rebuilding the tranny. I noticed the gear shifter/ indicator when i got it back from the shop i had inspect it. They had to replace the high beam switch and the guy said they would fix it free of charge since it wasnt like that before hand. Im really worried now i dont have the money to rebuild the trans. I just started driving a few days ago, boy do i have bad luck with cars.

I'll go out on a limb and say this probably isn't your trans failing. However, we'll wait for the report on that code. As previously stated, the code might only be related to the shift indicator being misaligned, which is potentially curable by a shift cable adjustment or repair of broken wires.

My '97 SE could never break the tires loose from a standstill, so I wouldn't be too worried about that. You have a taller final drive than a Grand Prix, so you can't necessarily compare the acceleration capapbilities of each car.

ninefittyone and Bandit--have either of you removed the throttle body and cleaned it? A gummed TB can really put the lag on acceleration. Bandit, you should definitely do this when you do your LIM gasket replacement. Remove all the sensors from the TB and soak it gasoline. Use a soft wire bristle brush to gently remove the carbon deposits.

ninefittyone--I had a similar issue with my 99. I replaced everything you mentioned and cleaned the TB. It ended up being my fuel pump. It was dieing slowly. At idle I was only getting 33 psi. When racing the engine it would drop. So, check your fuel pressures. And, how old is your fuel pressure regulator (mine was new at the time--GM recall)?

I'll look in my FSM tonight to see if I can learn more about that code.

FSM says DTC P1870 is Transmission Component Slipping

Says the DTC is set when excessive amount of slip is detected when the TCC is engaged.

Doh!

ninefittyone - Does the torque converter ever have a tendency to 'surge' or 'chuggle' when going up hills in lockup? Could be a bad TCC solenoid or valve body problem.

"Does the torque converter ever have a tendency to 'surge' or 'chuggle' when going up hills in lockup? Could be a bad TCC solenoid or valve body problem." Not exactly sure what youre talking about. But i can tell you this it shifts smooth occasionaly on heavier acceleration its kinda rough but other than that it shifts fine. I also hear a clunk coming from the rear of the car occasionaly when it shifts but that doesnt make sense since the tranny is in the front.

Good news. I changed the transmission fluid and filter and cleared the code and the cel light has yet to come on and the car seems to be shifting even smoother. Thanks for all the help

Kicking a dead horse maybe, but the misaligned gear indicator may be something as simple as going into the center console shifter and fastening the led that travels with the shifter. My 93 was like that until I fixed the cheap plastic assy. I now have the 98, and it is all done by a circuit board.. I call it MAGIC

The misaligned indicator cannot be the source of the code.

Sounds like excessive TCC slip to me. Keep an eye on your fluid color for a month or two. You may see a premature buildup of friction material.