My guess is either that module or the relay for the power side of that module has gone bad. If i'm not mistaken, that unit gets a signal to keep the radio on until the door is open.. and once a door is opened, that module cuts power to the relay which turns off your stereo. This unit also controls the chime and all that stuff..
EDIT: I just noticed the link to the module I posted is for an On-Star equipped vehicle, but your car should have a similar unit since it does not have On-Star.
A forum community dedicated to all General Motors truck owners and enthusiasts. Come join the discussion about performance, lift kits, wheels, tires, modifications, troubleshooting, maintenance, and more!