the supplied wiring harness comes with a relay and switch, the switch will have 3 wires going to it, mine was a white/blue/black wire, I cut the white wire (12v wire) coming from the relay to switch, connect the 12v wire and wedged it into one side of the 15amp parking light fuse that is in the fuse box next to battery. So the switch will be getting power from the parking light fuse, not from the relay. leave the white wire(12v) from relay connected to nothing( tape it off) Leave the switch in the on position and the lights will come on whenever the park lights come one or when it is dark out they will turn on when the DRL senses it is getting dark. When in auto mode, the park light fuse is activated when its is dark out so no need to turn the park light on for the fog lights.