See also:

Unable to Connect to OnStar Message
If there is limited cellular coverage or the cellular network has reached maximum capacity, this message may come on. Push Q to try the call again or try again after driving a few miles into anoth ...

Electronic Range Select (ERS) Mode
ERS or manual mode allows for the selection of the range of gear positions. Use this mode when driving down hill or towing a trailer to limit the top gear and vehicle speed. To use this feature: ...

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 the vehic ...