I'm Looking for a wiring diagram for a 2004 GMC W4500. Its a cabover built by Isuzu. The heater blower will run with the key off. Terry
I thought I should update this thread. I was given another Isuzu yesterday that has an emissions system fault. Solving that without wiring diagrams is not a likely outcome. Contacted the dealer and we were able to purchase access to their service portal for $75 for thirty days. Their site is easy to navigate and find the needed info, I'm impressed. Isuzu Truck Service Isuzu Truck Service www.isuzutruckservice.com