Output Shaft Speed (OSS) Sensor
WARNING: This page is about a different car, the 2005 Mercury Sable and 2005 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.
The output shaft speed (OSS) sensor is a magnetic pickup, located at the output shaft ring gear, that send a signal to the powertrain control module to indicate transmission output speed. The OSS is used for torque converter clutch control, speed scheduling and to determine electronic pressure control.