underhood wiring question??

[bp69f100mutt]

IMAG2042_20131219_205749.jpg

What is this plug for? It's located under hood near starter relay/solenoid, whatever you prefer. As you can see, its slightly damaged and modified. Came from junkyard while rebuilding truck, and has worked until recently. Now I have a FAST drain (.01 volts every 2 seconds, I stood and timed it last night), and so I'm replacing as much as I can to get the drain fixed.

The harness this is attached to has the alternator plugs on one end, regulator pigtail on the 2nd, and this, and a 2 prong pigtail at the 3rd. Cutting it all open and tracing wires, I have NO idea what the RED one is or even where it goes/went. There was a 14ga wire attached where other red is spliced that was connected to bat+ of relay, but I was using it as jumper on other harness. The yellow wire spliced into the jumble runs directly to the "A" terminal on the regulator plug. The other yellow wire (in between black w/ yellow and red) runs down along side the larger black w/yellow, merging into 1 larger, that runs directly to the bat+ of the alternator, and up to the splice nightmare. It's all seemingly interconnected, but frizzle-fries when re-attempting it. Connect it together, power in cab and at ignition, but melts once truck is running. And truck continues to try charging battery, but drains nearly instantaneously.

The wire harness I pulled today from my parts truck does NOT have this 3-prong pigtail, and when trying to jump the 2 positives of the 3-prong together, I had more wire melting. Without them, no power in cab or at ignition.

I have opened up this 2nd harness and traced all wires, everything is wired up the same, except instead of the wire spliced in to go to bat+ side of relay, it has a 16g fusible link, connected to the bat+ (alt) and "A" terminal (regulator).


No luck while looking for this 3-prong setup in any of the wiring diagrams (unless I'm blind and overlooked it multiple times). If someone else has this setup and know what it is for, or at least an idea, please help... I'm losing my marbles on this ordeal today. Been working on it since 7pm last night trying to figure something out, and I'm lost. Sorry for the long post, just wanted it to be known what I'm dealing with and what I've already tried. Less information to be requested

[mrollings53]

It looks like the connector between the alternator and the regulator. It's marked "A" in the diagram below. It also looks like someone hacked into it with reckless abandon. I'd be less worried about what it looks like right now, and get it to look like the diagrams on the tech page. That, or, you could install a 3G alternator and cut all that crap out.

http://www.fordification.com/tech/schematics_h.htm

[bp69f100mutt]

Actually, yeah it does! But, its in the wrong area... This plugs in right under the relay/ solenoid, and I don't have that field relay deal either... Don't think I've ever seen one either... Closest thing to that I've seen is the horn relay. I've thought about the 3g, but I want to keep it as original looking as possible by the time I'm finished with it. My grandmother has more pics of it that she's gathering up for me. I plan on taking the truck back as close to original as possible

[bp69f100mutt]

I have figured out that the small red wire on the 3-prong plug sends power into the cab, in some way. It's only about 7*F outside, so I can't be out there for too terribly long, the wind is unforgiving around here. Once I warm up enough to feel my face and talk again, I'll be back out to figure out what the yellow and larger gauged black/yellow wires are. As for the drain where I came upon this question, I have nothing. Even using the ol test light between battery and solenoid w/o cable trick is showing nada. Not sure where I'm going at this point, other than figuring out exactly what those other two wires are.

[bp69f100mutt]

Actually, upon closer look at the schematic mrollings53 attached, it seems more like "C" but a different plug style. There, like I said, is a 2-prong and a 3-prong plug instead of a single 4-prong square type... Maybe different styles used in different applications? The parts truck, upon further digging, is a 71 f100 custom. My 69's wiring came from a 72 SPORTcustom, as did the bed and a few other misc parts. Maybe that has something to do with it, not sure. Time will tell with more research