Key on and cranking power wire?

Ballast resistor and voltage regulator are long gone. I found the two blue wire connector for the resistor and it has power in the run position. I found a brown wire with no connector on it and it only shows power when I hold the key right in between run and crank.

I remember when I did this swap on my Scamp a couple years ago, that I back probed every single wire coming out of the 3 bulkhead connectors and the only wire that had power at the crank position was the wire for the starter relay. The Scamp was a running car when I did the swap. Now this Duster is exactly the same way. It seems like something happens when all the original wiring is not connected to anything.