WARNING: This page is about a different car, the 2003 Nissan Pathfinder. However, it is still accessible from the selected car via links, so may be relevant.
The revolution sensor detects the revolution of the out put shaft parking pawl lock gear and emits a pulse signal. The pulse signal is sent to the TCM which converts it into vehicle speed.
Fig 1: Identifying Revolution Sensor - 2WD And 4WD