Best to track them yourself then if things break in camp you know where your at, best if you have a multi meter, a must have bit of kit for off grid.........
A simple test would be to take cover off 12 pin and plug in to tug, check that breakaway is showing charging and the ESC led is on, pull the wire from pin 2 and see which one goes out, if both go out I would just disconnect the black near the breakaway and close the end on the wire returning to 12 pin, ESC should then be happy, with the lead from the breakaway I would perhaps cut the wire so you could mount a switch then run a van 12v wire to the switch, saves uneeded joins as well as neater, the switch would then allow you to isolate power to the breakaway, since its only a low wire a 10amp fuse owuld be more than enough........... I find it strange that they would run the ESC and breakaway power off the same circuit though but wouldn't be surprised........... I have only come across ESC connecting up with andersons.... I don't have one on Big Mal so haven't played with them a great deal just running repairs to others vans.
If you sit back and look at things like wire tracing its a bit like join the dots, a bit of thought and a meter or just a simple test light will answer your questions.... I have a length of wire with smalll insulated alligator clip on each end, I can use that to supply 12v to a cable then poke around at the other end with a simple test light ($3 at supercheap), when it lights up bingo found it...................... can go more tech with gadgets but often the old and simple wins with the wallet every time... BUT when you are testing stuff in van Never, Ever have it plugged into the 240 mains, mains lead should be pulled out, 240v switches are still live even when they are turned off...