I believe the relay is triggered by ignition on, and ground then completes through the harness at the six position ground terminal.I thought the volt meters only got their grounding through the steel mounting bracket to the back side of the dash plate.
Fixed my gen2 light and voltmeter by tracing the ignition circuit that was lacking voltage at both relays. They are powered by a .8 pink and black wire, 139F and 139G with the key in the on position. No power at the 4 terminals at the fuse block either. And no fuse where there should have been a 20amp.
All the head scratching and it was something simple.
The bright new yellow 20 amp was MIA so the ignition power was not bridging over to the 4 terminals on the left side, and not tripping the relay at Gen2 or the voltmeter.
With all the celebrating, I took it out for a drive only to find my Gen2 light flashing/flickering. Turning on my 24v LEDs make the flashing stop. More electrical work yet to do.