Anti-Lock Brake Speed Sensor
WARNING: This page is about a different car, the 2004 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.
The programmable speedometer/odometer module (PSOM) receives input from the rear brake anti-lock sensor. After processing the signal, the PSOM relays it to the powertrain control module (PCM) and the speed control module.