I think you are getting ahead of yourself. You need to "follow it back" and see where you are losing voltage. So far I have not heard the "ahah" from you on that.
It SEEMS to me you are missing the trees for the forest, or whatever. From what you have posted it appears that a COMMON cause is giving you low voltage to the system. You need to find at what point that is, and the post I made above, unless I misunderstood points right to the battery.
Or try this........instead of worrying about "so many things........."
Pick ONE circuit........like flashers, and chase them from end to end until you are certain they are working.
Then move to the headlights
Just why is it you feel the need to rewire the headlight dimmer? Is it/ the terminals damaged?
