dman, the wires could also be chafing where they pass through the backing plate from the magnet to the main wiring. The hole in the backing plate might be missing the rubber grommet that's supposed to be there. Check the wiring right up to the magnet, magnets very rarely go bad and just short out, especially with that few miles. If it does turn out to be the magnet you can order one online at
eTrailer. Just have the details from the sticker that should be on the axle tube to be sure you get the right parts.
BTW, nice work on the diagnostics! Feels good to have it fixed vs. waiting a month for the dealer to tell you they couldn't find any problems....
