DTC P0500: Vehicle Speed Sensor: Description
WARNING: This page is about a different car, the 2002 Nissan Xterra and 2002 Nissan Frontier. However, it is still accessible from the selected car via links, so may be relevant.
The Vehicle Speed Sensor (VSS) is installed in the transmission. It contains a pulse generator which provides a vehicle speed signal to the instrument cluster. The instrument cluster then sends a signal to the ECM.