You're tied to the dealer for this. GM is one of the worst manufacturers for "customer-unfriendly" business practices, and this is one of them. First they were real proud of the fact they were going from 200 authorized repair shops, (I worked for one), in the '70s, to six, to two, and that's what they have now, ... Two grossly over-priced repair centers. Next, in an effort to lock up all the lucrative repair business, they stopped allowing us to buy radio service manuals after 1994. With their 100 percent failure rate of their CD mechanisms, many people were installing aftermarket radios rather than paying $450.00 to have an AM / FM / cassette player repaired. To combat that, now they're building the Body Computer into the radio so it can't be removed from the vehicle. Starting with some 2002 trucks, some vehicles wont even start or run without the radio. You also can't install a good used radio from a salvage yard without at a minimum running to the dealer to have it programmed to your vehicle's ID number. That could mean towing the vehicle there, and you know they're going to be more than happy to program a radio you didn't buy from them.
It is also possible for a disgruntled mechanic to "lock" your radio electronically to all the other computers on the vehicle. You'll never know that was done until the day you have to replace the radio, then you'll find out none of the other computers will work. They all have to be replaced, and there can be dozens of them. That programming can't be undone either, at least not with the equipment found at dealerships. Imagine, ... A vehicle that's "not worth repair" because it needs a radio.
Sorry to sound so crabby, but I've run into so many angry car owners over this and other similar issues. I'd like to visit GM and pound some heads together on your behalf!
Now that I've vented, before you go to the dealer, you might want to run the radio with the engine off for a while. If the problem still occurs, it most likely is being caused by the radio. If it doesn't act up during this time, you might consider a wiring problem, especially if you have steering wheel controls. Vibration from driving may be activating a touchy button, or there could be a stretched or corroded terminal in a connector.
Thursday, April 9th, 2015 AT 5:31 PM