Inside your vehicle, it is common for the GPS signal strength to be reduced by the vehicle itself. Use the external GPS antenna, which connects directly to the T41 handheld via the MCX (micro-coaxial) port, to counteract this effect.
The external GPS antenna should be mounted to the top of the vehicle, where it has an unobstructed view of the sky. A properly installed antenna enables the T41's GPS receiver to calculate your location more precisely, because more satellite signals will be received, especially those that are high in the sky and otherwise blocked by the vehicle roof.
Once you disconnect the external GPS antenna, the T41 will revert to its internal GPS antenna.
