The Delco "Theftlock" radio on my wife's 2001 GMC Jimmy was locked and "inop" due to an improper code being input too many times. The dealership looked at the radio free of charge and rendered a prognosis that it could NOT be fixed. They offered to replace it for $500.00.
I then went to Beaty Chevrolet. They also examined the radio and could not fix it. There was no charge. But they advised me to drive the vehicle for at least 40 miles and bring it back to be reset. Their advice was right-on, but I reset it myself following instructions I had "Googled" on the internet.
The GM idea may be O.K.???, but the trouble an owner must endure to get it fixed (or not) is asinine at best!