I tried hooking up a brake controller in the diesel but it does not work. There are 4 wires, compared to the 5 in the gas (not coming out of the controller, from the truck). I get the decimal point but it will not give a readout or apply the trailers brakes. I already tested the truck with another controller and the same thing. Does anyone know if a fuse could be bad or some other problem. I have blue to blue, white to white and then the red and black wires are switched. This is the same way that it was done in the other truck that works.