Vehicle Speed Sensor: Description and Operation

Vehicle Speed Sensor Circuit:

Purpose:
The ECM will calculate vehicle speed based on a series of pulses provided by the vehicle speed sensor through the Digital Ratio Adapter Controller (DRAC).

Operation:
The ECM applies and monitors 12 volts to the VSS. The VSS buffer, DRAC, alternately grounds CKT 437 when the drive wheels are turning. This pulsing action takes place about 2000 times per mile and allows the ECM to calculate vehicle speed based on the time between pulses.

Location:
The Vehicle Speed Sensor is mounted on the transmission.