2006 GMC T8500 Service and Repair Manual

Built as the T8F042 straight truck with a low tilt cab, the 2006 GMC T8500 is a single-configuration model year, the same chassis sold as the Chevrolet T8500. Its turbocharged 7.8L inline-six diesel displaces 475 cubic inches and drives through the heavy-duty driveline and air brake system that define GM's largest tilt cab. This factory service and repair manual follows that exact 2006 specification, with procedures, specifications, torque values, wiring diagrams, diagnostics and maintenance schedules for the engine, air brakes, driveline, frame and cab circuits, so there is no guessing which values apply to your truck.

Engines covered

• 7.8L inline-six (475 cu in) — turbocharged, diesel

Body styles covered

• straight truck, low tilt

Trims covered

• T8F042

Known issues on the 2006 T8500. Two recalls are on federal record. The first covers trucks fitted with Bendix SR-7 brake valves, where an internal check valve might not seat, letting air leak and delaying spring brake application after the dash valve is pulled, which risks rollaway; dealers inspected and replaced the valve. The second found an air brake application valve assembly configured improperly, restricting air flow and lengthening emergency stopping distances; on T-Series trucks the air brake lines were rerouted. NHTSA also records two owner complaints, one each against the structure and the steering. The air brake, steering and frame procedures in this manual cover inspecting and servicing each of these systems.