See also:

Global Positioning System (GPS)
○ Obstruction of the GPS can occur in a large city with tall buildings; in parking garages; around airports; in tunnels, underpasses, or parking garages; or in an area with very dense trees. ...

How OnStar Service Works
Automatic Crash Response, Emergency Services, Crisis Assist, Stolen Vehicle Assistance, Vehicle Diagnostics, Remote Door Unlock, Roadside Assistance, Turn-by-Turn Navigation, and Hands-Free Calling ar ...

Head Restraint Adjustment
Do not drive until the head restraints for all occupants are installed and adjusted properly. To achieve a comfortable seating position, change the seatback recline angle as little as necessary w ...