Vehicle Speed Sensor
WARNING: This page is about a different car, the 2002 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.
Vehicle Speed Sensor (VSS) is mounted in transaxle. Transaxle output shaft turns a cable that is connected to the instrument cluster speedometer and transferred into a vehicle signal. VSS sends a constant pulse signal to PCM when vehicle is in motion.