See also:

Engine Cooling When Trailer Towing
The cooling system may temporarily overheat during severe operating conditions. See Engine Overheating on page 10‑20. ...

Fuel
For diesel engine vehicles, see “Fuel for Diesel Engines” in the Duramax Diesel Supplement. For Vehicles with gasoline engines, please read this. ...

Basic Trailer Wiring
All regular, extended cab and crew cab pickups have a seven-wire trailer towing harness. For vehicles not equipped with heavy duty trailering, the harness is secured to the vehicle's frame behind the ...