Vehicle Speed Sensor Check: Notes

The Vehicle Speed Sensor (VSS) circuit consists of a magnetic induction-type sensor, VSS buffer module (also referred to as the DRAC) and wiring. Gear teeth, pressed on outside diameter of output carrier assembly, induce an alternating current in sensor. This current is transmitted to the buffer module, where it is passed on to the PCM/TCM. The buffer module compensates for various axle ratios, and converts the signal to a square wave for use by the speedometer, cruise control and anti-lock brake system.

1. This test checks the VSS signal to the PCM/TCM.
2. This test checks the VSS signal to the buffer module.
3. This test checks the VSS signal.