Vehicle Speed Sensor
WARNING: This page does not describe the selected car, but rather 11 other vehicles, including the 1999 GMC Yukon, 1999 GMC Suburban, 1999 GMC Pickup, 1999 GMC Cab & Chassis, and 1999 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
Vehicle Speed Sensor (VSS) is a permanent-magnet signal generator located in transmission tailshaft housing or transfer case output shaft housing. A toothed rotor on tailshaft rotates near VSS, producing voltage pulses which are sent to VSS calibrator module.