Anti-Lock Brake Speed Sensor
WARNING: This page does not describe the selected car, but rather 11 other vehicles, including the 2002 Mercury Grand Marquis, 2002 Lincoln Town Car, 2002 Ford Crown Victoria, 2001 Mercury Mountaineer, and 2001 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.
The Programmable Speedometer/Odometer Module (PSOM) receives input from rear anti-lock brake speed sensor, which is located on rear axle housing assembly. The PSOM then relays the signal to PCM and speed control module.