Vehicle Speed Sensor: Description and Operation
PURPOSEDetects vehicle road speed and signals the ECU.
LOCATION
Speedometer head assembly.
OPERATION
Switching action frequency is interpreted by the ECU as vehicle road speed and used in calculations for fuel injection quantity, idle speed control, ignition timing control.
CONSTRUCTION
Sensor consists of a contact set and magnet that turns with the speedometer cable. Magnet movement causes the contacts to alternately open and close four times per cable revolution.