I get the switches from Freightliner dealers. Called interrupter switch. A momentary toggle switch... normally on, momentarily off. $7 bucks. Wired in-line on the park/marker/tail light circuit. When toggle is depressed, will open the circuit on all park/marker/tail lights without interrupting headlights. Exactly as the big rigs wired with the option. Us old-timer drivers will understand what you are trying to communicate using this set-up... . New breed drivers will only be confused and continue talking on their wireless phone headset while listening to satelite stereo and wondering where to find a shop to replace a broken headlight with no clue what CB channel frequency 27. 1850 mhz is. It's really sad out here nowdays! lol