Visit the dealer and their two grossly-over-priced repair centers. All of the dozens of computers on your truck answer to the Body Computer, and that is built into the radio to force you to have it repaired. Just one of the many tricks GM designed in to separate you from your money after the sale.
In addition, it is possible for a mechanic to press the "lock" menu selection on the GM scanner which electronically locks every computer module on the truck to the radio. Once done, that can't be undone. It's permanent for the life of the truck. If that was ever done, if the radio has to be replaced, every other computer must also be replaced. Got'cha. There is no valid reason for doing that, and I don't know why the engineers even designed in that option.
If I were to attempt a repair on that radio, I would get the correct model from a salvage yard, and negotiate a really low price since it has no value to anyone else, then switch just the face. The anti-theft circuitry doesn't reside in the face assembly.
Starting with '94 models, GM got really selfish and stopped allowing us to buy their radio service manuals, and without the part numbers in them, we can't buy parts. That's why you're stuck with their two repair centers and whatever they feel like charging.
Wednesday, February 17th, 2016 AT 3:19 PM