I have a 1999 Bonneville (52000 miles, garage kept, used sparingly) and yesterday when it was started the radio came on by itself. Furthermore, the buttons on the radio don't function. I can't turn it off unless the key is off and the door opened. None of them work at all. However the steering wheel controls work with the radio. What would cause this? Internal radio failure?
Sounds like a internal issue with the radio.