I have a 2007 Silverado 3500. I keep getting "Service Trailer Brake System" in the DIC. Here are some examples of when I get the message, but I do not always get the message in these examples. No trailer connected-Start truck, put in reverse and get message. Sometimes when a trailer is connected I will get the message right after pluging it in or just driving down the road. Some times it goes off when I use the turn signal with the trailer connected. Some of the time the message appears and the goes away and everything works normal, but some of the time the message appears and stays and I'm left with no trailer brakes. Occasionally I can shut the truck off and restart it and have it work normal, but not always. I have checked the fuses and they all appear fine. The truck does this with any trailer, but my other truck has no issues with the same trailers. The truck has been taken to different dealers, but they can never get the error message. Has anyone else had this problem, and have you been able to solve it?