Just bought this 2000 deville drove it about 200miles with no issues etc. trans was shifting perfect.
I parked the car overnight came back out the next day to drive it and the car wouldn't move at all.
I checked the trans fluid and nothing on the dipstick, I added 2 quarts and it said the level was fine. The next day i checked it again bone dry again. added 2 more quarts level was fine. checked it again the next day empty again. Yes i checked it with the car running in neutral, shifted through all the gears etc...

Is it possible that the Manul Lever position switch could have went out like in fords and its causing the pcm to make the car stay in neutral.

Or does this sound like a trans pump issue. or solenoid issue. I work on cars but this is my first cadillac Im stumpped.

 

Well....my first question would be, where is it leaking from?
The 4T80 trans is a little different from most trannys, in that the bottom pan doesn't really hold the fluid...the fluid is actually stored in the side cover, where you check the fluid level.
Having to add what so far has amounted to 6 quarts of fluid, 2 quarts a day, leads me to believe you have a leak. Should be fairly easy to find, if it is loosing that much fluid each day.
If the trans works fine once it has the correct amount of fluid in it, there's no reason to suspect a trans problem...you need to find/fix the leak, before it does turn into a trans problem.

The MLP would, NOT cause a no movement issue.
A broken pump drive, or pump, would cause the fluid level to be overfull when running.
A solenoid would NOT cause a no movement issue, either, with the possible exception of the PCS(pressure control solenoid), but...it would pretty much have to have fallen out of the valve body to cause a no go.

 

The car won't move at all acts like its in neutral in foward or reverse
Maybe its just super low on fluid. But no there's no visible leak
. Idk if I'm getting the trans hot enough to properly check the
Fluud level. Because I can't move the car at all, but I get the engine
Up to temp by letting it idle for 20 mins at least..
Once I put fluid in it shows on the dipstick. But the next
Day there's not a drop on the dipstick. So far I've added 5 quarts
I'm going to put a few more in. Maybe there was a leak but there isn't enough
Fluid in the trans to make it leak now.

 

I did a little reading, Could it be the pressure control solenoid? or possible the bad connector issue?

 

The PCS would have to have fallen completely out of the valve body to cause a no-go. IF you get the trans full of fluid, and it still will not move either direction, the most likely cause is a broken pump shaft. This may explain why the fluid is disappearing on you. When you add fluid to the side cover, it will stay up in there while you're checking it, and will show to be full. Once the engine is turned off, and it sits for a while(overnight), the fluid will drain off into the lower pan. Then when you check it next, it will be low/empty again.
With the pump actually working, that won't happen, because it will keep all of the fluid up in the side cover while running.
That trans will hold about 11 quarts total...you've added 5 already. Even if it was completely dry before you started adding fluid, the 5 quarts should at least get it to try to move, tho it wouldn't move very well.

 

If its the pump shaft would i have to remove the trans to replace it or is it something i can do with the trans still in the car? I am a mechanic