Just purchased a 2005 Fleetwood Excursion with Cat C7. The first time I used the coach I was pulling a heavy 3-axle trailer going down a steep grade. I switched on the Pacbrake, and when I looked back, my trailer brakes were smoking. I had to reach down and turn off the trailer brakes, which wasn't a really good thing to do. I believe that the trailer brake is wired in somewhere near the brake pedal. I know when the Pacbrake is turned on the brake lights also come on. How do I keep the Pacbrake from activating the trailer brakes?