do you get a rear light out indicator on your guage cluster(looks like a image of a car with lines behind it)? if not, then it is not the taillights, inner stop lights, or top mounted rear stop light. there is a current monitor that is seperatly fed by a 10A GUAGE fuse so if you are not getting that indicator, then it is not a stoplight(taillight). the 10A TAIL fuse also feeds the front parking lights(tiny bulbs inside the HID reflector), front side marker lights, license plate bulbs(2), and rear side marker lights. you will have to replace the fuse and inspect to see which one is out. if they are all working, then you will have to dig deeper and visually check sockets.Now this is happening to me as well... and I have no system... has anyone had this issue and successfully fixed it?