Covered Trailer Wiring

Update for Tues, 01-Nov-2022: The main trailer cord has been replaced with a new junction box. A blown fuse in our primary truck volunteer was also detected, and replaced.

Update for Thurs, 20-Oct-2022: I found the likely problem. The primary trailer cord is damaged and is probably the cause of the shorts. I will attempt a quick MacGyver repair on Saturday to get us through the competition, but larger work probably needs to be done.

Wed, 19-Oct-2022: I worked on the trailer lights both yesterday and today (connector shown). For a brief period yesterday, after reseating the left side tail lights and cleaning contacts, all of these were briefly working (using a simple 12 volt transformer and a multimeter for testing):

  • breakaway battery
  • running lights
  • left brake/signal light
  • right brake/signal light
The Connector Terminals

Unfortunately, after re-docking the breakaway battery and left side lights, there is a short between the running lights and ground. This is likely caused either in the battery junction panel, which also houses the wiring distribution out to the rest of the trailer, or the wires running under the trailer. The wires are old, and some of the insulation is brittle and cracking. I tested this a lot more today, but could not isolate the cause of the fault. More details are below.

Based on my multimeter readings, the current trailer connection 1, 2, and 3 are all basically shorted together (pins are depicted in this picture). Since I was able to get the running lights to work at first, this implies that the wiring is unreliable.

I plan to return to the trailer tomorrow (Thursday) afternoon about 2:00 PM and make one more attempt at isolating the wiring fault. I am reluctant to take aggressive action, as I have no way to test this connector/connection, but I’ll keep looking.