See also:

OnStar Overview
If equipped, this vehicle has a comprehensive, in-vehicle system that can connect to a live Advisor for Emergency, Security, Navigation, Connection, and Diagnostic Services. The OnStar system statu ...

Radio(s)
Radio with USB, CD, and DVD (MP3) : Press to turn the system on and off. Turn to increase or decrease the volume. BAND: Press to choose between FM, AM, or XM™, if equipped. : Select ra ...

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 ...