Vehicle Speed Sensor: Description and Operation

PURPOSE
The vehicle speed sensor reports road speed to the ECU. This information is used to synchronize emission systems and to adjust for various engine demands.

LOCATION
The sensor is mounted in the back of the speedometer cluster.

CONSTRUCTION
The sensor is a reed switch that is controlled by a rotating magnet inside the transaxle. As the magnet passes under the sensor the contacts close momentarily, resulting in a ground at the ECU. Four pulses are produced for each sensor revolution.