Anti-Lock Brake Speed Sensor
WARNING: This page is about a different car, the 2002 Ford Ranger. 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. Information from the PSOM is used to help determine shift scheduling, torque converter clutch operation and Electronic Pressure Control (EPC).