Vehicle Speed Sensor (VSS)
The VSS generates a pulsing signal when the rear wheels turn. With the ignition switch in RUN or START, battery voltage is supplied from fuse 2 through the Black/Yellow wire to the VSS. The sensor is grounded to G101 by the Black wire. The Yellow/Red wire is supplied approximately 5 volts by the speedometer and other control units that are in the circuit. The VSS generates a pulsed signal in the Yellow/Red wire by intermittently grounding it. The number of pulses per minute increases or decreases with the speed of the rear wheels.