Vehicle Speed Sensor: Description and Operation

Vehicle Speed Sensor:

PURPOSE
Provides vehicle speed information to the ECM.

LOCATION
Built into the speedometer head.

OPERATION
The VSS consisting of the lead switch and magnet is built in the speedometer. As the magnet turns with the speedometer cable, its magnetic force causes the lead switch to turn ON and OFF. Such ON/OFF frequency increases or decreases in proportion with the vehicle speed and is sent to ECM as pulse signals.

ECM uses it as one of the signals to control the ISC solenoid valve.