IF the green LED was on, then it had to be wired to something. With those partly stripped leads, it does appear to have never been connected. Maybe what you saw was reflected light that made it look like it was on.
With red and black wires, it's about a 99% sure thing it's supposed to be fed via a 12v DC line. For safety's sake, I would call the factory, talk to Dave Ponser and find out where exactly it should be wired