You lost me. X413 is a separate connection that is routed along the main body harness adjacent to where the liftgate harness attaches. If it was there, then all you needed to do was plug the UVC portion of the liftgate harness you purchased into it. If it was not there, aside from the camera +, -, and shield which you should extend from the C-pillar, the blk/wht wire needs to go to a chassis ground, the pink wire is switched battery voltage, and the dark blue wire should be jumped to the reverse lights. I can't answer your voltage reduction question other than to say that if you are using the factory reverse camera, my assumption would be that it already contains whatever it needs in terms of a voltage dividing circuit. Hope that helps.