2001 Yukon XL 165,000 miles but in excellent shape. Everything, I mean everything works perfectly until it didn't. It's my daily, so two weeks ago I get in, start it up and the radio does not work. You can see the green light in the background but it won't come on at all no matter how many times you try! Drove it that day then parked it. It sat for just over 24 hours and when I tried to start it the battery was dead, graveyard dead. Charged it, started right up but still no radio. However, with the key turned forward but the engine NOT running the radio comes on and plays as it should. But once you start it no radio. It sits and the battery drains. I took out the radio and the battery does not drain. I install a used factory radio and back to ground zero, no radio, battery drains but radio plays when key turned forward. I ain't gotta clue. Have you ever encountered this?