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 5 ('97-'99 models), 02 Heater Relay ('00-'01 models), or Heated Oxygen Sensor Relay ('02-'04 models) 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 about 5 volts to the ORN wire. The vehicle speed sensor (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.