No. You don't use existing wiring for it at all. That relay hooks to the battery, the lights, the switch and a ground. It is triggered by the switch and opens a current flow between the battery and the lights. It allows you to run larger amperages without needing an expensive switch to handle the load.
[URL="http://www.jeepforum.com/forum/f22/yellowtail-build-1262933/"][COLOR="Yellow"]The Yellowtail Build[/COLOR][/URL]
[QUOTE=Jeremy Clarkson - Top Gear Botswana Special]Why don't all cars have no doors? When I come to power I'm going to make it a rule because this is just better.[/QUOTE]