I bought a used f350 with factory tow package. The previous owner removed the trailer brake controller. I put a tekonsha primus controller in the truck with a plug n play harness for the controller. The controller shows there is power being sent to a trailer and a trailer is connected. This happens when I step on the brake pedal when the truck is first started and I don't have a trailer hooked up. It goes away after several brake applications. I have disconnected the trailer plug harness and it still shows this.