One problem related to dash wiring has been reported for the 2004 Chevrolet Trailblazer. The most recently reported issues are listed below.
I bought a 2004 Trailblazer with a factory installed tow package, including electric hookup. When I hooked it to a travel trailer, the tblazer sent to charge to the trailer for battery charge, interior lights, etc. The dealer, gold motors in newport, oregon, said there was no problem. However, it still refused to work. I took the car to a local mechanic. He discovered several wires in the box housing the wiring manifold at the front driver side of the engine were cross-wired. He straightened it out at the cost of two hours labor. If this is the standard quality of gm quality, they should be allowed to go bankrupt.