To your point with the harness, so I have an 04 f250, I put it back together after rolling it over (new cab and bed) had some minor wiring issues reverse lights stay on, blend door doesn’t actuate (I replaced the vacuum pump and module), fuel gauge isn’t working likely the wire in the tank, now to my current issue. I drive it for about a week since getting it together, ran smooth no hiccups, I dropped my daughter off with her mother and left the truck running (20 min) after a 30 min drive, I went to pull out of the parking lot made it 10 car links and it killed out cold, turns over like there’s no load, oil pressure gauge isn’t building. Got it home tore it down after doing a few pressure checks found a hole in the ipr screen. Went ahead and installed motorcraft sensor, hpop, o rings etc. got it fired up let it run getting all the air out of the system ran smooth for 30 min then shut off, fired it back up and feathered the throttle, stayed running and I pulled it back in the shop it shut off again and fired right back so I moved to under the hood and started to install the intake and the piping shifted the harness across the top of the motor by the oil/fuel filter housing and it shut off, so I fired it back up and touched the harness and it killed out, I looked over the loom in that area and saw no damaged wiring and have been unable to restart it, I am hearing that crank over like there is no load behind it like it did the day it killed out on me on the road. Any help would be great or ideas, maybe I am overlooking something? Thanks allDisconnect the oil switch and use a wire to short the single contact in the connector to batt ground. The needle on the gauge should move up to "normal". If it does, your sender is bad or you have a bad connection to it. ...and I don't care if it's new. If it stays down, you need to take a close look at your harness.
For the harness... With the truck running, you can push on the harness with a stick or some other non-conductive thing at different locations to see if you can get the needle to jump. If you can, whatever/wherever you pushed on last is the problem.