Voltage drop at ballast resistor

Quite all right. I'm partially disabled at 69, myself, with arithritic like conditions, and in particular, neck problems. "Crawling around" under a dash is VERY tough on this old guy

The last several "gist" of what you have posted indicate that it's all "right there" in/ at the bulkhead connector or the under-dash harness. Might be time to find a (younger LOL) local friend/ help to help pull the cluster and access things.

I waste no time........I pull the seats!!!!