Vehicle Speed Sensor
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 1991 GMC Pickup, 1991 GMC Cab & Chassis, 1991 GMC C3500 HD, 1991 Chevrolet Pickup, and 1991 Chevrolet Cab & Chassis. 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. A toothed rotor or tone wheel fastened to transmission tailshaft rotates near VSS magnetic sensor coil, producing AC voltage pulses which are sent to DRAC. This sensor assembly takes the place of speedometer cable and related gear hardware.