What do electrians use to track mystery wires? Got several in my coach, that had 3 house battery banks, plus the chassis bank added pre 1995 when the PO purchased it. Can see it disappear but haven't seen it re-emerge anywhere. This one is black insulation positive cable. Got 7 red hots that we're all bolted together by a mobile tech when the isolator failed. Got a negative that appears to be wired to the port alternator connection.
Buy a tone generator wire tracer from Amazon, HD, or? Cheap and works like a million $ Easy to use.
Amazon.com: tone generator wire tracer: Electronics (https://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Delectronics&field-keywords=tone+generator+wire+tracer) The inexpensive ones work well. Got ours at HF.
Pierce
Pierce's wire tracer is a handy addition to anyone's electrical bag. I use mine regularly.
Bought a Sperry tone tracer from cheapo Depot for about $40. Took it home and spent hour messing with on 4 & 6 ga wires unsuccessfully, lost signal on 4 ga wire in about 2 feet.. Took it back and got the $78 Fluke Pro3000 which is supposed to be good for 10 miles of small guage wires. Ok signal mid coach, detectable signal on 4 ga at front of 36' coach without both ends detached. I think I got this snake pit figured out. Will do a smoke test in the morning as all ohm readings to ground appeared normal. 9:00 and tools put up so time for a beer.
Fluke makes excellent products. I was one of those spending $24 at Harbor Freight. I wanted to see where the extra wires in the back went. I was easily able to find their termination up in the vicinity of the steering column with the inexpensive tone generator. They are about 35 feet away but the tone was strong when I got to within three or four inches. This was exactly as I expected.
Pierce
Habor freight is on the other side of town, hd is only 10 minutes each way. Fluke is generally $$$ professional grade quality. This $80 tool is my first Fluke purchase. I will report back on the smaller guage wire success. Finding a wiring fault is sometimes a needle in a haystack, and coaches have lots of wires.
A good tool will make it easier to do good job.
TOM