Trans problem with 96 Grand Prix - need a little help, please

[Boatman]

I have a 96 GP that just developed a sudden trans problem. A little background first. It's a 3.1 L with 80 K miles. No mods, daily driver. Engine a trans have run like a watch to date.

Then yesterday... Upon startup, car slips like mad in drive. Feels like it's got almost no clutches. Revs to 4,000 plus in D on the brake. Shifting to 1st, it has a little more bite. Revs to maybe 3,500. Still slips like mad. No funny noises. However, in reverse, all is normal. Trans pulls hard. Can't hold the car against the brake.

Fluid level is OK and is still a dark red. No burnt smell.

Car is throwing a code (service light on dash) but I don't have a code reader yet (one is coming tomorrow).

Problem happened immediately with no warning, and reverse is strong so I tend to doubt a bad pump or clutch pack.

I'm an old hand wrencher. Built lots of cars, motors and rebuilt more than a few trans in my time, but all old school. Nothing with computers, till now.

If this were a TH 350 or 400, I'd suspect a valve body, but it isn't.

Anyone got any advice on where to start, or do I need the code first?

Thanks...Steve

 

[Trannyman95]

It likely isnt anything electrical causing your problems. The last time you drove the car everything worked perfectly normal? Have you tried letting it warm up a good while to see if anything changes? There are a number of things that could cause your problem but they are all internal. If pulling it into manual 1 doesnt help much then your problem is likely in the input clutch drum or you have a stuck valve in the valve body. Will the car pull itself at all in D-1? If it just feels like its stalling up really hard like its starting off in 3rd or 4th gear then it could be another problem.

 

[Boatman]

Got the codes...

Computer threw three codes:

P0753 - Shift Solenoid A Circuit
P0758 - Shift Solenoid B Circuit
P1864 - Manufacturer Controlled Transmission

Trannyman:

Thanks very much for the response.

Warmed the car up to normal operating temp. No change in behavior. In D, the car can get moving, but it feels like the torque converter is behaving like a 4000 RPM race converter that never does lock up. In 1st, it pulls a little better, but nowhere like normal. Starts in 2, 3 and D are pretty much the same. Lots of RPM and not much acceleration.

Just for the hell of it, I tried clearing all the codes. The first two stayed off but the third code (the seemingly most vague of the three) threw again.

No shuddering, no noises. Still pulls in reverse just fine.

Any idea where to start?

Thanks...Boatman

 

[Trannyman95]

I would check fuses first thing. If there is no power at all going to the transmission then it will take off in 3rd gear and will take off in a lower range if manually pulled into a lower range, I believe only 2nd gear and not 1st. There should be a pink wire on the harness that plugs into the front top area of the trans, this will be your 12v + wire and should have ignition voltage. If not then this is your problem.

 

[Trannyman95]

I just looked at the wiring schematic for your car and the fuse should be labeled TCC/Cruise 15A fuse, Underhood fuse box

 

[Boatman]

You're good - right on the money!!!

Thank you very much for the informative post. You are clearly an asset here and you got the problem right on the money. Before I saw your post, I was googling my codes and came up with a post on a Lumina board. A guy had the same problem as me and the same three error codes. Someone posted back that didn't have a trans problem, he had a blown fuse.

Went right to my fuse box and found that the 15A minifuse, middle right was blown. Couldn't read the box cover too well but looked like it said TCC. If so, that makes a lot of sense - no power to the torque converter to lock up. Put in a 15A fuse, cleared the codes, drove it for a half hour and it's fine. Dives great and no codes.

Seems like that was the problem. But I'm wondering - why did the fuse blow in the first place?

Any ideas.

Thanks...Boatman

 

[Trannyman95]

Glad to hear that fixed your problem! The fuse could have blown for a number of reasons but likely wasnt from a bad solenoid in the trans. One of the wires that comes off of that fuse runs to a switch on the brake pedal and then back out to the TCC solenoid to dissable power to it during braking so the engine wont stall. More often than not its a bad switch or wiring problem that would blow the fuse. If it happens again then maybe you will have something concrete to search for but intermittant problems can make you chase your tail for a long time.