Q: What is the importance of the Vehicle Speed Sensor (VSS) and its location in Chevrolet Astro and GMC Safari?
A: The Vehicle Speed Sensor (VSS) informs the Powertrain Control Module (PCM) of vehicle speed and controls the Torque Converter Clutch (TCC). For 1992 and earlier models, the VSS is behind the instrument cluster; for 1993 onwards, it's on the transmission's rear extension. For the former, remove the instrument cluster and then the VSS screw. For the latter, raise the vehicle's rear, disconnect the electrical connector, and remove the retaining bolt to extract the sensor. Installation is the reverse, inspecting the O-ring seal and checking transmission fluid levels.