It plugs in, but I had to pull some pins, and switch their position to get it right. (cant explain what to do, it's just trial and error)
Even now, when it's on high beam, to get all lights to go to low, when I hit the hi-low switch, I have to momentarily push in my light switch. It's a minor annoyance. The lighting is sooooo much better than before, and I do a lot of driving at night.
Eric
PS The way I have the harness setup, when I'm on low, or high beam, I have all 4 lights on. This made a huge difference. Even factory sport trucks cant do this!!:-laf :-laf