One wire alternator wiring? with OEM harness?

So i want to bump this to the top.
Factory ammeter stopped working with this conversion.

I ran an independent, 4 gauge wire direct to battery from alt.

I know ammeter is fairly useless, but kinda annoyed at another dead factory gauge.

I traced wires from the Oe regulator back to the plug on the firewall, and unplugged it. Water temp was only other one in it. And it also died long ago.

Also randomly lost gauge backlights.

Did unplugging this voltage regulator harness plug kill a ground??

Even hooked oem charge wire back up temporarily and ammeter still inop.

Thx guys