'99 4.6 Battery & Alternator Wiring

[Barimpact]

I just got myself a 1999 Expedition XLT 4x4 (with the dumb auto that I will be doing the brown wire mod) with the 4.6 engine. It was an absolute steal at $300 clean title, and it runs and drives, only 108k miles. However, the previous owner informed me that the alternator drains the battery when it is connected.

I started looking into the issue and found that the wiring is kind of a mess. Some looks aftermarket from the sound system he used to have and some looks oem, but there are just wires kind of everywhere.

Here's what I'm dealing with:
1) a big red wire that goes from the battery positive to a mega fuse (200A I believe) that then goes to the top terminal of the alternator.
2) zip tied to this wire is a ********* wire with a yellow stripe, disconnected at BOTH ends
3) a thick black wire that goes from battery positive to the starter
4) a thick red wire that splits into 2 wires that goes into a harness leading down towards the starter
5) near the starter there are 2 black wires that come out of a harness that is connected to the frame rail, just behind the upper control arm mount. These 2 black wires come out of the harness and connect together to a ring terminal. This terminal is NOT connected to ANYTHING, it is just suspended in the air. It has multimeter continuity to the red wire that splits into 2 wires mentioned above in (4).

With this configuration, connecting (3) and (4) to battery positive allows the truck to start, run, and drive, even with the others disconnected.

If anyone can give me insight to what these might go to I would really appreciate the help. I've googled some charge system wire diagrams for the 4.6 but I'm really not convinced I have all the OEM wires. Thanks in advance.

 

[Barimpact]

Here's some pictures of the damage:

 

[Barimpact]

And a few more:

 

[stamp11127]

Welcome to the site. Best advice I can give you is to get the factory service manual (includes wiring diagrams) off ebay. Usually less than $20 for the cd/dvd.

Once you know what wires need replacing, I'd hit the local junk yard for good replacements.

 

[Barimpact]

I found a part out Expedition and took the wiring off of that and replaced all the aftermarket junk. For future reference or if anyone else may run across the problem, here's what's going on:

There is a black wire with an orange stripe that goes from the top alternator peg to the bottom peg of the solenoid against the firewall.
There is a positive wire that goes straight from the battery to the starter.
There is a positive wire that goes to a special 2 ring connector that attaches to BOTH terminals on the solenoid against the firewall. Really only goes on 1 way.

Easiest thing for sure was pull the parts off a different car. The harness for the 5.4 and 4.6 are very similar year to year, but not the exact same for every year, as many forums will tell you. At least for me, the '01 5.4 Eddie Bauer had an extra ground wire that was supposed to attach to the starter, and the starter currently on my 4.6 did not have a place for this, and works perfectly as is. It also routed down to the starter a slightly different way, but this was not an issue.