I think I’m gonna buy the manuals and wiring diagram but plan to keep working while I wait on it.

I noticed a damaged black/orange wire which matches one with a fusable link (circled in green) and I plan to do something with it, but I want to make sure there is no damage farther along.

There is a massive round connector (all the wires in the bundle!) going through the firewall behind the drivers side battery and very close to the fuseblock inside. (Blue arrow)

How do I disconnect it? It is hard to reach or see. Is there a latch, or something to twist?

Access on the inside is if anything worse!

 

me thinks you green circle wire may just be your issue.

 

The green circle wire is a problem but not THE problem.

I just stripped the damaged insulation and removed the part between the two tears. The copper is intact, just a little dusty/dirty. It obviously needs help to prevent it shorting out to other things, but it is still doing its job.

An ohmmeter from the battery side of that wire to there read 0.3 which seems good enough.

I still can’t figure out how to disconnect the big circular thing and check to the end of the wire.

 

I don't see where you mentioned what year this model is .
on a 99 , the harness to the fuse box , is connected with 2 10 mm bolts , that are captured , they will not fall out , and are a bit long winded .

 

It is a 1990. E250, Club Wagon XLT if that matters. The international 7.3l diesel does matter.

I got the fuse block loose, two long Philips head screws. It is attached to a steel plate bracket with three more screws that blocks access to the firewall connectors. Got that out too.

I’m waiting on wiring documentation since I can’t just beep it out as the power doesn’t seem to be getting there at all.

I should work backwards from fuses I know aren’t working, I suppose.

 

The true factory manual does have the E series stuff in it. I know because its more stuff I need to scroll by when I'm looking up F350 info.
I got the best one from a post on here. My apologies to who put it up there as I cant remeber your name. My thanks to you as its helped a lot!
Perhaps someone else can link you to it.

 

I believe there is a bolt right in the middle of that round connector that holds it together. Probably 10mm or something close. You'll have to wiggle the wires to the side to get to it. If you haven't already, disconnecting the batteries would be wise until you get it pulled apart and can make sure the wire won't short out.

 

Any idea which side of the firewall the bolt is accessed from? The engine side would require me to remove more stuff, I think.

On the engine side, it sticks out more (enough to be two halves of a connector) and there seems to be an orange ring that could be a lock or something.

 

Never mind that last, I found the bolt on the engine side.

Now I’ve got something in the way that I can’t wiggle it around to disconnect.

Looks like a mechanical cable run; both the emergency brake and the hood release are nearby. The position seems more likely for the brake.

As usual, access sucks.

As for the batteries, I took them out to get access so they are very disconnected!