2012 GMC Sierra 2500 HD Service and Repair Manual

This factory service and repair manual for the 2012 GMC Sierra 2500 HD describes a truck of two engines, three cabs and four trims: the 6.6L turbocharged diesel V8 of 403 cubic inches or the 6.0L gasoline and flex-fuel V8 of 364 cubic inches, in a 4-door crew cab pickup, a 4-door extended cab pickup or a 2-door standard cab pickup, badged Denali, SLE, SLT or WT. Procedures, specifications, torque values, wiring diagrams and diagnostics are organized by system so that any of those combinations can be followed straight through.

Engines covered

• 6.6L V8 (403 cu in) — OHV, turbocharged, diesel
• 6.0L V8 (364 cu in) — OHV, naturally aspirated, gasoline or flex-fuel

Body styles covered

• 4-door crew cab pickup
• 4-door extended cab pickup
• 2-door standard cab pickup

Trims covered

• Denali
• SLE
• SLT
• WT

Known issues on the 2012 Sierra 2500 HD. Two of the three recalls filed here fall on the restraint system: frontal air bag inflators that can rupture once their propellant has degraded, driving sharp metal fragments into the cabin during a deployment. The remaining one covers a fire extinguisher shipped with the truck that can clog and fail to discharge in an emergency. Owner complaints total 60, led by 11 on air bags, eight on the electrical system and seven on the structure. Restraint system diagnostics, the wiring diagrams that feed the sensing modules and the body procedures behind them are all in this manual.