Wires on Regulator:
Yellow - Green wire from coil
Yellow - Yellow wire from coil
Red - Positive DC feed into wiring harness (negative side grounded)
Black - Tied into common ground
Blue - Not hooked up
My only concern was using the same ground for A/C and DC.
Second, not having the blue wire hooked up. Seemed to me like it was just a regulated resistance to keep the battery from overcharging and didn't matter one way or another as batteries are for suckas (edited)