I'm just throwing thoughts in the air....

The door locks, windows etc each have their own fuse, but all share a common ground.....runs to check FSM....

Ok... looking at the schematics... we need to check ground G202. This is the main ground point for all those circuits. It is located behind the carpet, next to the parking break pedal. Inspect and report back please.

That means its drawing too much power(amperage) either the load is too high because of many circuits, or you have high resistance in the circuit due to corrosion.

How are the wires going into the ground bus look? Do you see any green inside of the connector?

They are clean. I was thinking of running a thicker ground wire to that bus. Would that help?

You can try running one straight from the battery negative terminal and see if that makes a difference.