Vehicle Speed Sensor: Description and Operation

With the ignition switch in ON (II) or START (III), battery voltage is supplied from fuse 24 (fuse 12 without SRS) through the BLK/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 YEL/WHT wire. The vehicle speed sensor (VSS) intermittently grounds the YEL/WHT wire which generates a pulsed signal in it. The number of pulse per minute increases/decreases with the speed of the car.