One-wire alternator gauge hookup

[Back in Black]

I just hooked up a new one-wire alternator on my truck. I also removed all the external regulation stuff. There was one extra wire which I taped up that ran to the cab. The alternator guage doesn't work and I was wondering how the gauge communicates with the alternator. I thought maybe the gauge monitored the volts going into the cab via the heavy red wire. Maybe not. Has anyone been down this road.

Thanks

Jason