I've heard a lot of "get a seven pin" on here. And "get a brake controller." What exactly does a brake controller do? I know some older trailers would have a sense line tied in to the brake light wire, so it could trigger the brakes electrically. As opposed to surge brakes. Is there some kind of fancy electronic signalling that trailers need these days, to make their brakes work? How essential are they with a relatively light trailer like a pup? (My tow vehicle is probably going to be my '06 Colorado, which natively comes with a 4-pin. Probably, because of a very long story involving it being parked on the street, an idiot not watching where they were driving, and an insurance company- there's just enough uncertainty for me to not put it in my signature).