Ok it has been a lot of years since I installed my fog lights (OEM) but there is a harness that comes with them that has a relay in it. it gets routed down the main harness and then behind the engine to the left side and you hang the relays with the others that are there. then from there back up to the lights and the switch. this is what makes it a OEM plug and play unit. The wire colors remain the same but the gauge size changes to small for the trigger signal. I guess it does not get the amps running thru it, just the larger wires. main power purple to the relay and of course the actual light wires and plugs. Just guessing as I am not electrician. I must say I enjoy reading Decosse's post as there is always something to learn