Intermediate Shaft Speed (ISS) Sensor
WARNING: This page is about a different car, the 2004 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
The intermediate shaft speed (ISS) sensor is a magnetic pickup that sends planetary sun gear speed information to the powertrain control module (PCM). The ISS is mounted externally on the center of the case.
The PCM uses the ISS information to aid in determining pressure requirements.