2000 Pontiac Montana Transmission Problem

Hello All,
I am a semi-very mechanically incline guy, and usually like to work on my own things, In my many years of working on my own vehicles, I have yet to come into the problem I am having currently with my Montana.

So here goes, when the vehicle is first started, it will shift fine until it gets heated up. Then the car pops out of gear into neutral as soon as you let off the gas, or if it idles to long in park it will go straight into neutral when put into gear. Now I can turn the van off as soon as it pops of of gear, wait about 5 seconds for it stop turning and it pops right back into gear so i can move it across my yard or where ever I need to move it for the moment.

I have been doing alot of reading on this subject, I had a code one time of incorrect gear ratio, then I had a code of torque convertor clutch circuit stuck on, I have reset the codes and have yet to make them pop back on.

So pretty much wondering if anybody has any ideas or insight on this situation, or would it just be best to pull the transmission and replace it.

thanks,
Brandon

When you experience the problem try all of the other ranges of the transmission. If it shifts into nuetral while driving or it wont move, put the shifter into another range. One of the first steps of trans diag is to know excactly what you do and dont have. Try Rev, Drive, 3rd, 2nd, and Low range. Start in Low and manually shift up through the gears and note what happens. Don't jump into a replacement yet.

When you experience the problem try all of the other ranges of the transmission. If it shifts into nuetral while driving or it wont move, put the shifter into another range. One of the first steps of trans diag is to know excactly what you do and dont have. Try Rev, Drive, 3rd, 2nd, and Low range. Start in Low and manually shift up through the gears and note what happens. Don't jump into a replacement yet.

Until the transmission heats up, it shifts fine, as for when it stalls likes its in neutral, it will not do nothing in any of the gears until I turn the car off and let it set for 5 secs, it makes a little wine noise, almost like a P/S noise but its the transmission. U can hear it wine down when you shut the motor off, and then when its re-started it right back into gear. thats why I haven't jumped into the replacement. because when its cold it shifts perfect, so it can't be the clutch, I am thinking its the pressure switch, or the TCC selenoid. I am not sure, its just something that has puzzled me for months. I have though long and hard, and have researched until I get aggrevated. So I decided to research some more.

They do have pressure control solenoid and valve body problems. Dtc's p1811 and P0742
can "usually" be repaired with a valve body, spacer plate, P.C. solenoid, and a TCC PWM solenoid. As far as it not moving at all and making a whining noise points toward a pump or a torque converter stator. If it whines for a few seconds afer the engine is off the only thing that could be spinning is the stator. Everthing else will stop rotating with the engine off. A line pressure test will tell alot also.