2018 GMC Sierra 3500 HD Service and Repair Manual

This factory service and repair manual for the 2018 GMC Sierra 3500 HD keeps to two engines and four trims. The engines are a 403-cubic-inch 6.6L turbocharged diesel V8 and a 364-cubic-inch 6.0L naturally aspirated V8 running gasoline or flex-fuel, both overhead-valve; the trims are Base, Denali, SLE and SLT. Five bodies are in scope, covering standard, extended and crew cab pickups plus cab and chassis versions with two or four doors, and the service content is organized by system rather than by model.

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

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

Trims covered

• Base
• Denali
• SLE
• SLT

Known issues on the 2018 Sierra 3500 HD. Six recalls are on the federal record. Two point at the optional engine block heater cord and its terminals, which can short and raise a fire risk. One covers front seat belt retractors assembled with the wrong torsion bar, so the belts may not restrain properly. Another involves a roof-rail air bag inflator whose end cap can separate and be driven into the cabin. The last two are fuel storage: a front tank overfilled until it contacts the driveshaft, and a rear tank that can collapse and stall the engine. Fourteen complaints cluster on brakes, steering and wiring, all diagnosed here.