Diesel Data: Automotive Repair

Vehicle Speed Sensor: Description and Operation

Vehicle Speed Sensor:




Vehicle Speed Sensor (VSS):





PURPOSE
Provides vehicle speed information to the Electronic Control Module (ECM).

OPERATION
The vehicle speed sensor, located in the speedometer drive gear, is a magnetic reed switch that rotates in conjunction with the transmission output shaft. It sends the ECM on/off signals. The ECM interprets the speed at which the on/off signals occur into vehicle speed.