Check the shift linkage under the vehicle at the transmission.
If I'm reading the question correctly, the transmission won't worm in forward or reverse If so, this is a sign of a transmission with worn out solenoids, clutches, gears, etc. Get the car to a transmission specialist and plan to rebuild or replace.
Search Cadillac DeVille Questions
Cadillac DeVille Experts
Find great deals from top-rated dealersTMSearch
Related Models For Sale