Stoplight switches have come a long way from the basic "on-off" switch initially used. Today's switch more likely indirectly controls the stoplight by sending a request to the PCM to "command" the lights on. Today's switches are still mechanically actuated by the brake pedal, but many are "self adjusting." DO NOT push the plunger in before installing! Once installed, a quick press of the brake pedal will set the plunger stroke for you!