Vehicle Speed Sensor: Description and Operation

The Vehicle Speed Sensor is a gear-driven Permanent Magnet Generator housed in the vehicle's transaxle. This sensor generates a sine wave output with a frequency proportional to vehicle speed. The Engine Control Module (ECM) converts this signal to an output that is switched to ground at a frequency of 4000 pulses per mile at the DK GRN (389) wire output. This output is pulled up to 5 volts or greater by the components that use these speed signals as input.