Thread: 99 GTP (P0756 error code)

Hello all. New member and first time posting. I looked around using the search and didn't find too much about this but i'm hoping I can find a fix. Car has about 100,200 on stock engine, tranny. No weird problems before this. Just driving on highway about 60 and realized it wasn't shifting into that 4th gear and shortly after I realized it the check engine light came on. It gave me the error code P0756 (shift solenoid B Performance/ stuck off). Deleted it off but it'll come back every time now. What causes this? Can I fix this? Thought it may have been throttle position sensor because car did stall on me twice after getting off highway, could only move after manually putting into first. (Rpms were also bouncing but we have already changed it out with a new one) This threw the code P0742 (torque converter clutch circuit stuck on) but after deleting it, it hasn't come back. Fluid is full, bright red.

Really hope I don't have to replace transmission as we got this car from a lot and still paying payments...
Any help would be greatly appreciated.
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Ok this is how we got it fixed (2/14/2017)

Upon pulling the pan there was no filter installed, normal clutch wear.
Side cover was pulled at least twice, be careful, if the metal gasket falls apart just order another and save yourself the headache.

We took out the entire valve body and cleaned it thoroughly. The problem was that normal clutch wear had plugged up one of the orifices and this wouldn't allow the plungers to move. The solenoid screens where also plugged up but I had already ordered new ones.

Everything was cleaned nicely and reinstalled. Somehow during the install we messed up the shifter cable so be cautious with that. Now it shifts smoothly and much faster than it ever did before. My 2-3 shift is very very rough still but it takes hold instantly. At least the transmission shifts haha. This is in no way a how to guide exc. Just some summed up info in how we fixed it. Read through the posts to get more info I probably missed. Definitely could not have done it without the help of the senior members who provided some helpful tips!

I wouldn't say you have to replace the transmission but it may need a new shift solenoid because of that code.

Pulling the pan won't help much, all the valve body parts and solenoids are in the side cover on the drivers side.

These are the same symptoms (codes) I saw in my brother in laws trans. Turns out the torque converter clutch let go and sent crap through the whole trans. Filled the valve body up with grit and caused multiple solenoids to stick. Pan was full of grit. Enough that a large doughnut magnet could no longer capture it all.

Not saying that's your problem, but it seems odd that you would have multiple solenoid malfunctions at the same time. Might be worth pulling the pan to inspect.

its all the same fluid, its pumped through out the tranny.

Originally Posted by BrandonHall10

These are the same symptoms (codes) I saw in my brother in laws trans. Turns out the torque converter clutch let go and sent crap through the whole trans.

Originally Posted by Revan365

Thanks for the input. I'm hoping not.. Seems like the car was owned previously by and older couple who at least maintained it. When purchased with 96k miles fluid was bright red. Its still red now but slightly darker. Really hoping it won't be the torque converter 

He had less than 50k on a SERTA reman trans when the TC let go.

might be a help.

https://youtu.be/pcfahwKPM7M?t=1151

All of the solenoid retaining clips should be accessible from the front (outside) of the VB. You said it's been rebuilt... It's possible the builder put the TCC retaining clip on from the back. Look very closely for the legs of the clip.

Originally Posted by Revan365

Could the valve body need taken off?

If the retainer clip is on the back side, that's the only way you're going to get to it. If you do pull it, go ahead and order/grab a gasket(s). I like the bonded separator plates.