Vehicle Speed Sensor (VSS)

VSS is a Permanent Magnet (PM) generator mounted in transmission or transfer case. The VSS sends a pulsing signal to either the PCM or Digital Ratio Adapter Controller (DRAC), which passes the signal on to the PCM. PCM then converts this signal into Miles Per Hour (MPH) by monitoring the time interval between pulses. PCM uses this sensor input in controlling converter clutch engagement, shift speed, etc.

On all models, a VSS buffer is built into the DRAC.