[cknuth]

       
Here I go again - resurrecting an old thread with (probably old) questions.    My rear 12V electrical cabinet contains a Hopkins "Electronic Power Taillight Converter."    It is similar to products made by Draw-Tite and others (photo attached.)    It promises right on the unit to "protect tow vehicle from trailer shorts."    Its inputs come from the trailer light breakers, but it pulls separate power from the main terminal block in the cabinet.   And only the yellow and green outputs are hooked up to the trailer connector. The remainder of the trailer connector wires are coming from their factory before-converter sources. Currently the trailer lights work, but the turn signals are reversed.

I plan to run dolly lights and wireless toad lights, plus a brake controller that takes its signal from brake lights. 
Do I need this Converter?    Why might it have been installed in the first place?    And, to stay on topic, should I set the switch to Foreign or American?

Chester has no recollection or documentation of it, so it's probably been on there since the original owner.
Thanks!
Chuck