[tdangle]

Old Kelsey Hays brake controller. Was operated by fluid from the braking system and the wiring is +12v to the controller and the blue wire (I think) goes to the trailer brakes. I believe there may also be a ground wire or they use the mounting and brake line connection as the ground. Should glow red when stepping on the brake or manually moving the lever on the front. I don't recall how to adjust the sensitivity. Here is a link for a copy of the manual http://67-72chevytrucks.com/vboard/s...d.php?t=782914