Vehicle Speed Sensor
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2002 Mercury Sable, 2002 Mercury Mountaineer, 2002 Mercury Grand Marquis, 2002 Mercury Cougar, and 2002 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
Vehicle Speed Sensor (VSS) is a variable reluctance or Hall Effect type sensor that generates a waveform with a frequency that is proportional to vehicle speed. When vehicle is moving slowly, sensor produces a low frequency signal. As vehicle speed increases, sensor produces a higher frequency signal. PCM uses this signal to control fuel injection, ignition timing and transaxle/transmission shift and Torque Converter Clutch (TCC) scheduling.