GMC SIERRA DENALI Navigation Manual page 40

The system may not be available or interferences may
occur if any of the following are true:
•
Signals are obstructed by tall buildings, large trucks
or a tunnel.
•
Metallic objects are located on the dashboard.
•
Satellites are being repaired or improved.
•
Aftermarket glass tinting has been applied to the
vehicle's windshield.
Do not apply aftermarket glass tinting to the vehicle's
windshield or place metallic objects on the vehicle's
dashboard. Glass tinting and metallic objects will
interfere with the system's ability to receive GPS signals
and may cause the system to malfunction.
If you are experiencing a problem, see "Vehicle
Positioning" and "Problems with Route Guidance"
following for more information.
2-30
Vehicle Positioning
At times, the position of the vehicle on the map may be
inaccurate due to one or more of the following reasons:
•
The road system has changed.
•
The vehicle is traveling on slippery road surfaces
such as sand, gravel and/or snow.
•
The vehicle is being driven on winding roads.
•
The vehicle is being driven on a long straight road.
•
The vehicle is approaching a tall building or a large
vehicle.
•
The surface streets run parallel to a freeway.
•
The vehicle has just been transferred by a vehicle
carrier or a ferry.
•
The current position calibration is set incorrectly.
•
The vehicle is being driven at high speeds.