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 ECM or Digital Ratio Adapter Controller (DRAC), which passes the signal on to the ECM. ECM then converts this signal into Miles Per Hour (MPH) by monitoring the time interval between pulses. ECM uses this sensor input in controlling converter clutch engagement.

On all models except 3.1L, 3.8L and 4WD equipped with 4L80-E transmission, a VSS buffer is built into the DRAC. On 3.1L, a VSS buffer is located between VSS and ECM. On 3.8L and 4WD equipped with 4L80-E transmission, VSS buffer is built into ECM.