This lever at the bottom of the column locks an automatic transmission in Park or a manual transmission in Reverse whenever the ignition is turned off. The lever moves an inner tube tied to the rotary part of the steering column collar. When you place the automatic shift selector in Park or a manual transmission in Reverse, you are moving this lever, which turns the tube and collar to line up a slot with the upper actuator. Once the slot and actuator are lined up, the transmission is locked. It cannot be locked in any other gear but Park (automatic) or Reverse (manual).