Intermittent electrical issues have to be the worst kind (except for fire, did that today also). My Prodigy P3 controller would occasionally give me the Output Shorted message and of course no braking from the trailer. Couldn't find anything obvious so decided to replace the wires that run through the inside of the axles. The photo shows what I found, a bare spot rubbed right through the wire insulation to the wire. Last trip I had found a bare spot where the wire had been rubbing where it comes out of the axle and assumed that would fix the problem. Appears OK so far. We'll see next trip.