Global Positioning System (GPS) Limitations

The GPS cannot detect the vehicle's position or elevation during the following instances:

For the first 5 to 10 minutes after reconnecting the 12 volt battery (this process can take as long as 45 minutes).
When the satellite signals are blocked by tall buildings, mountains, tunnels, large trees, inside parking structures or large trucks.
When the GPS antenna is blocked by metallic window tinting or by an object placed above it in the vehicle. The GPS antenna requires a clear unobstructed view of the sky.
When there is no satellite signal output (signal output is sometimes stopped for satellite servicing).
When the satellite signals are blocked by the operation of some electronic aftermarket accessories including, but not limited to non-OEM in-dash entertainment units (amp, CD players/changers, radar detectors, theft recovery systems, etc.) and mobile phones placed near the navigation system.

The accuracy of the GPS is reduced during these instances:

Metallic window tinting above the GPS antenna.
When only three or less satellite signals are received (Four satellite signals are required for accurate positioning).
When driving near high tension power lines.
When the satellite signals are blocked by the operation of some electronic aftermarket accessories including, but not limited to non-OEM in-dash entertainment units (amp, CD players/changers, radar detectors, theft recovery systems, etc.) and mobile phones placed near the navigation system.
When the satellite control centers are experiencing problems.