1989 f350 crew cab 7.3 idi 5 speed manual. Power windows and door locks.

I have no power to the ignition or anything in the cab. I can't jump start starter solenoid. Worked on it 8 hrs now and sometimes I will see dash lights come on faded though. One time while working with fuse panel all lights came on and had full power turned key on and off s few times, didn't crank the truck though, turned key back on and then no power again. Here is what I have replaced.
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Starter solenoid
Ignition switch
Starter
Voltage regulator
Pulled fuse panel from under dash and checked wiring.
Fuse panel has 12v in fuses I pulled
battery cables seem new with little or no corrosion, driver side neg cable is a little swollen but not bad.

I rewired the 4 fusible links to starter solenoid (one was burnt out), 3 yellow and 1 Black/orange.

I unplugged the entire glow plug system .

Cleaned with wire brush drill all grounds
both front engine battery grounds
frame to passenger engine ground and used new larger gauge wire
Rear engine block ground to firewall. And used new larger gauge wire

What I've found so far. Batteries are consistent 12.5V. The 4 fusible link wires coming off the starter solenoid I reattached with new wire and rings, the black/orange wire is carrying 1 volt when not attached to the starter solenoid. Why is this? Does it mean it is missing a ground down circuit in the cab? When attached to the starter solenoid with the 3 yellows and other wires the voltage reading at the solenoid drops from 12.5V to 12.39V. this means the black/orange wire is drawing power right? I am stuck here currently.

Several days ago when turning ignition on the whole electrical system would pulse and guages and gp controller would click on off really quickly. Truck would start(no gp needed its warm enough here now) then the rapid blinking would stop after about 5 seconds.

I have no idea, any suggestions will help. Transmission ground connection? I have never been so dead in the water with my 6.9, this 7.3 is leaving me dumbfounded.

 

Do the battery cables look home made? They love to leave people stranded in parking lots.

 

I had an issue with my truck that left me dead, and battery cables looked fine. It either wouldn't crank, or would crank real slow. Tested starter out of truck with jumper cables and it kicked and spun hard, back in the truck, nada... Finally hooked a jumper cable up direct from battery down to starter, and it cranked no problem. So even though they looked fine, something in the battery cable was screwed.
Replaced it and no more problems. Can't remember if I cut an end open and found a slight bit of corrosion? Either way it surprised the heck out of me, and it wasn't even the original cable.

 

Still no power to cab at all. Here is where I am currently tracking. I have all wires off starter solenoid except large red battery cable coming from batt. I will start attaching the 4-5 other wires that go on the hot side of the starter solenoid and as I attach each wire I am checking for a voltage drop at the solenoid. The voltage drops to 10v when I attach the black/orange wire which runs into fuse panel. Then I attach another of the yellow wires which I believe runs to passenger side door panel and voltage drops to 1. These two wires also carry around 1 volt unattached to the solenoid.

Why would they hold voltage unattached to soleniod? Because there is a bad ground somewhere back feeding the circuit?

Why do these two wires cause voltage to drop at the soleniod? A bad ground somewhere? Could a bad connection for power doors or cruise control cause this bad of electrical loss?

 

you have a short in something connected to those wires.
unfortunately the only way to find it is to backtrack through the connections.