Programmable Speedometer/Odometer Module (PSOM)
WARNING: This page is about a different car, the 1995 Ford RV Cutaway, 1995 Ford Econoline, 1995 Ford Cutaway, and 1995 Ford Club Wagon. However, it is still accessible from the selected car via links, so may be relevant.
PSOM receives input from Rear Anti-Lock Brake Sensor (RABS). The RABS is mounted to rear axle differential. The PSOM signal is used by speed control module and the PCM.