Vehicle Speed Sensor (VSS)
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2000 GMC Yukon XL, 2000 GMC Yukon, 2000 GMC Sierra, 2000 Chevrolet Tahoe, and 2000 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.
VSS is mounted in transmission. VSS produces an AC signal with a frequency proportional to speed at which transmission assembly output shaft rotates, which is also proportional to vehicle speed. The AC signal is sent to cruise control module assembly and speedometer by Powertrain Control Module (PCM). The signal is sent at a rate of 4000 pulses per mile, and the PCM converts number of pulses per mile per second to determine speed of vehicle.