See also:

Trailer Towing (CTS-V and Coupe)
The vehicle is neither designed nor intended to tow a trailer. ...

Sunroof
On vehicles with a sunroof, the switches are on the overhead console. The sunroof only operates when the ignition is in ON/RUN/START or ACC/ACCESSORY, or in Retained Accessory Power (RAP). See ...

Diagnostics
OnStar Vehicle Diagnostics will perform a vehicle check every month. It will check the engine, transmission, antilock brakes, and major vehicle systems. It also checks the tire pressures, if ...