Voltage problems, cutting out when hot

I’ve now gotten away from the under hood wiring, for now after tracing all wires I’m fairly confident the under hood charging Harness is OK and the problem lies under the dash. I was using my voltmeter to tone test wires from point to point. (I’m sure this isn’t the right way either but it’s what I know.)
When toning wires from bulkhead to ignition switch and from bulkhead to fuse block I figured out that the red wire at the ignition switch J1 would have continuity tone to ground at the fuse box at the bulkhead and at the switch connector.
I can’t find a solid breakdown of the fuse box/block to figure out what fuse is what in each location.
What I have found online doesn’t paint a real clear picture of what goes where and tracing the wiring with the red wire showing continuity at multiple points it is almost impossible to pinpoint where to start.
I’m starting to feel like the seatbelt interlock system cars are different enough that schematics for a regular dart are not the same.
Sorry to jump out of charging into dash harness but I’m positive it is directly related to all of my problems.
Thanks