Vehicle Speed Sensor: Description and Operation

With the ignition switch in ON (II) or START (III), battery voltage is supplied through fuse 1 and the YEL wire to the Vehicle Speed Sensor (VSS). The sensor is grounded by the BLK wire to G101. The speedometer and other control units in the circuit supply 5 volts or more to the ORN wire. The VSS intermittently grounds the ORN wire which generates a pulsed signal in it. The number of pulses per minute increases/decreases with the speed of the car.