See also:

Four-Wheel Drive
If the vehicle has Four-Wheel Drive, you can send the engine's driving power to all four wheels for extra traction. ...

Reporting Safety Defects to General Motors
In addition to notifying NHTSA (or Transport Canada) in a situation like this, please notify General Motors. Call 1-800-GMC-8782 (1-800-462-8782), or write: GMC Customer Assistance Center P.O. Box ...

Tow/Haul Mode Light
This light comes on when the Tow/Haul mode has been activated. For more information, see Tow/Haul Mode on page 9‑26. ...