Jimmy, the big rig dealerships do the same thing. I told a shop I had ABS problems, and I thought the trailer was the culprit. The trailers today, due to having ABS on them run an ECU. That ECU has to communicate with the tractor ECU. When they don't a code is thrown just like on our cars. The tractor dealer replaced the ECU. The trailer shop, said it was the tractor. It was just the opposite. I had already told them I didn't get a code when I pulled a different trailer...They just don't listen to those who drive the vehicle day in and day out...The ECU's in both the tractor and the trailer were fine. They were l sending a code that something was wrong. Idiots, I'm telling you...