Quote Originally Posted by NoMoreScrapLeft View Post
Idaho you seem smart. if you look at the pic there is a red wire hanging from the tounge. it runs to the wheel hub. I know this is the trailer brake but what is that wire hook to on the tounge? Is it missing something..battery?
Yes, that would be wired into the trailer plug as others have mentioned. If you were to wire that directly to a battery it would lock up your brakes. A brake controller controls the amount of voltage applied to the brakes as the truck is braking.