I have a 1995 Audi A6 with a automatic transmission. I just bought the car a few weeks ago and just found out that my backup lights are not working. I have replaced the brake light switch, the cruise control switch, the back up light are new, the fuse is good, there is no voltage at reverse light sockets. I was told that it may be the backup light switch. Does anyone know where the back up light switch or sensor is located? Can really use your help!!

Anthony