Good evening everyone, i hope the weekend it treating you all well! I have a few questions for you. Currently i have been experiencing the normal hard shifting that happens with a lot of the 4T65E-HD transmissions. Im 99.9% positive that it is the pressure control solenoid. The only reason i know this is when i use my autotap scan tool i can watch the line pressure, and after 2 shifts that the computer considers "bad" (Shift took longer then it should) the pressure goes to almost 100 PSI and never varies from there (DTC P1811). This happens when shifting into any gear. Even further i can clear the codes "On the fly" with my aeroforce scan gauges and the problem goes away immediately (Only to return within ten minutes). It happens more frequent and faster as the outside temp gets hotter. Everything that i have read on this site so far leads me to believe this is the case. So, looking into the problem more i have seen many posts on possible fixes. I would rather not find a "Cure in a bottle" because this might only mask the problem. I really want to get in there and replace the solenoid valve. So, my question is can i just remove the some odd 15 bolts around the edge of the transmission cover and just slide it back far enough so that i can access the solenoid? Some other components like the air box and shift cable will probably be removed just for ease of repair. It looks like the bonnevilles have enough room to maybe do this just because of the large engine bay. Here are some pictures i took of my car.....

I would change the fluid and filter before I did anything like tearing into the transmission. https://www.gmforum.com/t278423/

As far as pulling the tranny cover off and doing the work without dropping the transaxel. I'm not sure if that'* doable or not.

Good Idea Purplehazeir, however i have changed the fluid and filter on it 3 times since i have owned the car. 25,000 50,000 and 75,000 miles(Im at 86,000 right now) and the fluid has always been nice and red. When i change the fluid it will help the problem for lets say, 5000 miles or so, but then it comes back......