Reverse Servo
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.
Apply air pressure to reverse servo passage. A dull thud can be heard when low/reverse band tightens around planetary assembly. Movement of ring gear should also be detected.