See also:

If the Vehicle Is Stuck
Slowly and cautiously spin the wheels to free the vehicle when stuck in sand, mud, ice, or snow. If the vehicle has a traction system, it can often help to free a stuck vehicle. Refer to the vehicle' ...

Customer Assistance Offices (U.S. and Canada)
GMC encourages customers to call the toll-free number for assistance. However, if a customer wishes to write or e-mail GMC, the letter should be addressed to: United States GMC Customer Assistance ...

Accessories and Modifications
Adding non-dealer accessories or making modifications to the vehicle can affect vehicle performance and safety, including such things as airbags, braking, stability, ride and handling, emissions syste ...