2004 GMC W4500 Forward Service and Repair Manual
This factory service and repair manual for the 2004 GMC W4500 Forward takes in two bodies and two engines. The truck reached customers as a low crew cab straight truck or a low-tilt straight truck, under the single W4S042 build code, with a naturally aspirated 6.0L overhead-valve V8 of 364 cubic inches on the gasoline side and a turbocharged 4.8L inline-four of 290 on the diesel side. Everything is presented by system, with procedures, specifications, torque values, wiring diagrams and diagnostics for each.
Engines covered
- 6.0L V8 (364 cu in) — OHV, naturally aspirated, gasoline
- 4.8L inline-four (290 cu in) — turbocharged, diesel
Body styles covered
- Straight truck, low crew cab
- Straight truck, low tilt
Trims covered
- W4S042
Known issues on the 2004 W4500 Forward. One recall attaches to the 2004 W4500 Forward, covering fuel switching manifold solenoids that lack resistance to water and salt intrusion. When one fails, fuel delivery goes wrong and fuel can overflow out of the filler neck, where an ignition source turns a spill into a fire. A single owner complaint is also on record, and it concerns the service brakes. Both areas are documented in this manual: fuel system components, circuits and diagnostics on one side, brake procedures, specifications and torque values on the other.
