97GTP Stuck in Third Gear

[thumper89]

Last week my 97 GTP with 150,000 miles started taking off VERY sluggish when shifted from park. Feels like its in 3 rd gear all the time. When shifting from Park, the driver information center lights go out while in reverse and neutral, then come back on when everything below is selected. The airbag light also comes on also.Took it to a local autopart store and they checked the charging system and said the alternator was only putting out about 11 volts and said that could be the problem. Same problems with the new alternator, but now they say it kicking out 17 volts, which would explain why every light on the car is SO bright now. This all only happens about 95 percent of the time, the rest of the time everything is absolutly normal. Any ideas?

[BNaylor]

Is it just a bogging condition or actually stuck in third gear? How is it when you manually shift? It sounds like a possible short in the transmission range switch circuits. The 17 volt alternator output is definitely on the high side.

[troy1]

blowen fuse will make it do wrong gear starts does it ever shift?.. Check the box under the hood I think its labeled "TCC"

[thumper89]

When I manually shift to 1st if feels like it starts in 2nd and manually shifting to 3rd or drive feels like 3rd. The 17 volt alt. only happens sometimes. Other times it is normal and the brightness of the lights is normal. Checked every fuse on the car and all were good. I think now it may be a short in the harness because last night for the heck of it I reached down and pulled and tugged on it while the car was running and it ran and shifted fine untill I got home, then when I put it in park and back to drive, the problem returned.

[BNaylor]

Thats a good possibility since you have a '97 GTP which were prone to wiring problems depending on the date of manufacture in the production year.

It sure sounds like you are missing the 12 volts to the TCC circuits which happens to be the same 12 volts that feeds all shift solenoids like the 1-2 and 2-3 and the TCC-PWM solenoid. The symptoms would be an overring to get going like having the brakes applied while accelerating and feeling like it is stuck in a gear.

Try disconnecting the 20 way umbilical connector at the top left of the tranny and reseat.

[thumper89]

I have tried everything everyone here has suggusted (THANK YOU for the help), but still no remedy. and yes , it does feel like having the brakes applied while accelerating. I stripped the harness from the connector on top of the tranny to the brain and found no obvious breaks. I was told the harness is prone to shorts from the air cleaner box rubbing on it. I was wondering where the tranny gets its power(umbilical connector or elsewere)? Wondering if a short could be there. Also, Is there a way to test the shift solenoids from the outside or am I just going to have to not buy gas for a week and take it to a tranny shop.

[BNaylor]

The tranny gets power solely via the umbilical connector. The 12 volts for the solenoids comes from the engine compartment fuse box. The grounds/low to each solenoid like the shift comes from the PCM module.

You can check solenoid coil resistance at the 20 way umbilical connector tranny side.

1-2 shift - pins A-E 19-24 ohms
2-3 shift - pins B-E 19-24 ohms
TCC - pins T-E 10-12 ohms
PCS - pins C-D 3-5 ohms

Readings at 68 degrees F.

The 12 volt power in can be measured at pin E at the umbilical connector plug.

[thumper89]

After all the testing and prodding was finished, the car was dead. Would jump start, then shortly die. Returned alt and swapped for another new(rebuilt) with same results. A friend said the old alt probably fried the batt so I pulled it out to have tested (tested good). Thats when I discovered the battery was leaking at the top and the acid had disolved 95% of the harness that runs behind it, including the trans wires. Suprised it still ran at all. Any thoughts on repairing the wires or replacing them without major harness replacement, and I still have to figure out why the alt is not charging the battery.