A bad brake switch or a loose ground stud behind the right rear trim panel that can affect the taillights. The hi mount is a separate circuit and that's why it continue's to work. Boefore going into the rear panel I would suggest checking the taillight connectors first, but it not likely the problem. Its hard to diagnose a problem as such without the vehicle but maybe this will help. If you look through the post Waldorf did with his rear view camera install I think he has a picture that shows the stud I'm referring to. :smileup: