Vehicle Speed Sensor: Description and Operation

How the Circuit Works
With the ignition switch in ON (II) or START (III), battery voltage is supplied through fuse 13 and the YEL wire to the vehicle speed sensor (VSS). The sensor is grounded through the PCM. The speedometer and other control units in the circuit supply 5 volts or more to the BLU/WHT wire. The vehicle speed sensor (VSS) intermittently grounds the BLU/WHT wire which generates a pulsed signal in it. The number of pulses per minute increases/decreases with the speed of the car.