Intermittent Brake Short Solved
My prodigy controller started showing an intermittent brake circuit short message at the very end of a trip back from Yellowstone.
After reading here, I guessed the problem was that I had burned through a magnet.
I took the trailer in for service, and it turned out one of the magnets was severely worn and all of the brake shoes were cracked. I also had them repack the bearings at the same time, and they also replaced the leash on the breakaway switch.
I picked the trailer up and left for Yosemite. About 100 miles into the trip, the dreaded SH message showed up on the brake controller again. I took it easy and slow on the rest of the drive, and spent time going over the wiring inch by inch at the campsite.
I found that one of the leads to the breakaway switch was pinched under the aluminum propane tank cover. Over time, the insulation had worn away. Re-routing the wires so they were not pinched and about six inches of duct tape from the campsite host temporarily solved the problem. This week I will do a more permanent job.
So learning lesson is to make sure your breakaway switch wiring is not getting pinched underneath your tank cover... Seems like a design flaw that the wire routes that way where it can get pinched in the first place.