Rear Vehicle Speed Sensor
WARNING: This page is about a different car, the 2008 Subaru Tribeca, 2008 Subaru Outback, and 2008 Subaru Legacy. However, it is still accessible from the selected car via links, so may be relevant.
This vehicle speed sensor is a Hall element type sensor and is externally mounted on the extension case. It detects the rear wheel speed in terms of the peripheral speed of the rear drive shaft and sends pulse signals (22 pulses per rotation) to the TCM.