Breakaway Wire Short-circuit

Over the last couple days, Cary has helped me sort through a wiring issue that may present a potential issue to some of you, but it is easily detectable. A 5 second inspection could save you a couple days of troubleshooting.

While searching for an unrelated electrical issue in behind the removable fuse panel cover I discovered a completely fried wire leading to the +BAT post connection. As all my electrical systems for the trailer seemed to be functioning correctly, I elicited Cary's help to identify that it was the emergency brakes breakaway wire and he advised to look near the near tongue for a possible short.

The 7-wire trailer cable is wrapped and zip-tied along with the breakaway wire at the tongue of the trailer and typically rests on the frame of my trailer (YMMV), like so, when towing.. View attachment upload_2019-9-5_14-26-54.png

Unfortunately, the breakaway wire on the underside was in direct contact with the frame and it chafed through, shorting out...

View attachment upload_2019-9-5_14-30-3.png

The chafing and short was not at all visible (like it is in the pics) until I pulled the cable away from the frame.

The last section of wire leading to the battery was of a smaller gauge so it literally took all the heat and fried, leaving the thicker 14 ga that runs under the trailer unaffected. I replaced the burnt out section of wire at the battery as well the area where it shorted., and gave it a good ballistic nylon wrap.

From what I can tell, this is one of the few (only?) electrical components of the trailer that is not fuse-protected, hence the wire melt-down; I'm not even sure that it could be fused, given what current spike the emergency brakes might want to (or need to) draw when the breakaway switch is activated.

Mine was quite possibly a one-off issue, but just the same it may be worth a quick inspection, and some extra wire protection, if required.

Cheers,

Steve

 

I just discovered this same issue on my 2012 560 Ultra. Heat-shrink crimp connectors were used, but the plastic shrink material had a tiny hole in it that was filled with blue corrosion powder. This was on both connectors. Perhaps someone had used the “uninsulated” crimping tool on it, hard to say.

I cut out both connectors, stripped, crimped with new connectors, and shrunk them with the heat gun.

My sense is that with the insulation compromised, they could intermittently short when wet, completing the circuit, applying the brakes, draining the battery. I wasn’t able to find the holes in the insulation until I cut out the connectors. If you see a light blue-green powdery deposit on the connectors it’s time for new ones!

Attached is a shot of what the bad connectors looked like once I’d cut the cable ties.

Thanks for writing this up Steve, these bad connectors were easily diagnosed with your hints and the wiring diagram. Like you, this was in the process of replacing a really damaged battery. I’m sure this contributed to it, but there was also another short to ground, harder to troubleshoot, which probably killed the batt faster.

 

Thanks Seth.

Mine appears to have been an instantaneous one-off short, while yours was more of a long-term deterioration. Either way, no fun to root out, nor deal with. Especially on the road.

At the last CICO Cary advised that my wire contact configuration wasn't terribly common. But in their always-changing always-improving build protocol, it wasn't necessarily a unique way of doing things either. CI apparently now does a quick visual for this potential problem on any trailer coming in for service, and have discovered at least one wire that was headed in the same direction as mine.