Output Shaft Speed (OSS) Sensor
WARNING: This page is about a different car, the 2003 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
The OSS Sensor is a magnetic pick-up which detects the park gear teeth rotation and sends a signal to the powertrain control module as an indicator of the transaxle output shaft speed. The OSS signal is processed by the PCM for shift scheduling and inputs to other control modules such as: Electronic Speedometer, Trip Computer, Speed Control, Adaptive Damping, Auxiliary Warning and Radio CD.