ac delco radio code for tta

My friend had a radio that was locked in his TA and it was the mute button on the steering wheel. It took some time to get it to work though... I heard the contacts get gunked up and the actual button assembly as been known to go bad.
The unlock is using the mute button with the Ignition switched to ON.

Unless someone unplugged the steering wheel controls.. then your SOL.
You can't just "hit" the mute button. You have to press it AND hold it down with ign on till the loc light goes out and the radio works. If this don't happen then the radio controls on the steering wheel may have an issue.