One problem related to underhood wiring has been reported for the 2004 GMC Sierra. The most recently reported issues are listed below.
I had purchased my Sierra 1500 from chesrown dealership of delaware ohio. I had the truck for less than 60 days. I loved the truck very much but was very upset when an electrical fire started in under my hood. This happened the day after thanksgiving and since I had the factory stereo system I had no explanation for the start of the fire. It took the fire department a couple of minutes to get there and by that time the fire had spread from the engine throughout the wires down the firewall and into my trucks entirer. All that I could do was watch in horror as my truck was engulfed in flames from a far. I attempted to stop the fire from spreading inside and my hand was burnt. When the police used the the fire extinguisher from their cruiser it seemed to give it oxygen and spread it faster. I was devastated.