2003 cadillac deville transmission wont move went to the store 5 min away came home trasmission wont drop in any gear

I tried the DIY service and repair manuals from a website and it actually helped me repair transmission problem in my jcb 3cx site-master. it wont move forward or reverse, engine is good both solenoids for forward and reverse work.
I don't have much technical knowledge but I just followed it step-wise, and works
perfect! got it from www.reliable-store.com

This trans you will ether have to get it repaired or replaced you can try changeling the trans filter and fluid and I would add a can off sea foam for trans too it

Hi,
Get your Automatic Transmission Fluid (ATF) checked, it could be old or low. May be time for Transmission flush, too.


GL,
Td

DEXTRON-III Automatic Transmission Fluid

does the clutch push normally or is the linkage broken not disengaging clutch, and then does shifter move around or locked and wont move, loose linkage in shifter or gears are jammed inside transmission and something went, if shifter wont move at all then trans is jammed inside and needs repair.

So I'm guessing that when you put it in reverse and it won't move. If you put it in 1st it moves but won't shift to 2nd? And it rattles. And since you have a 4.9 in it the transmission is a 4T60E. I am going to guess that you broke the reverse reaction shell in the transmission.

replace park neutral switch located beside the shift cable

Tranny low on fluid. When you stop or turn it all goes to one side causing the problems.

Easy to buy, difficult to replace as it is in a very awkward place on the top of the end of the transmission near the right drive axle location. Requires a hoist and the need to disconnect a few things to get at it.

the first one is your security light on?