Cadillac 2008 CTS Navigation System Owner's Manual page 58

Global Positioning System (GPS)
The navigation system determines the position of your
vehicle by using satellite signals, various vehicle signals,
and map data.
At times, other interferences such as the satellite
condition, road configuration, the condition of the vehicle
and/or other circumstances can interfere with the
navigation system's ability to determine the accurate
position of the vehicle.
The GPS shows the current position of your vehicle
using signals sent by the GPS Satellites of the
United States Department of Defense. When your
vehicle is not receiving signals from the satellites,
a symbol appears on the map screen. Refer to
Symbols on page 2-7.
2-42
This system may not be available or interferences may
occur if any of the following are true:
•
Signals are obstructed by tall buildings, trees, large
trucks, or a tunnel.
•
Objects are located on the rear shelf of the vehicle.
•
Satellites are being repaired or improved.
•
After-market glass tinting has been applied to the
vehicle's rear windshield.
Notice: Do not apply after-market glass tinting to
the vehicle's windows. Glass tinting will interfere
with the system's ability to receive GPS signals and
cause the system to malfunction. You might have
to replace the window to correct the problem.
This would not be covered by your warranty.
For more information if the GPS is not functioning
properly, see If the System Needs Service on page 2-44
and Problems with Route Guidance on page 2-44.