[VetteVet]

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Originally Posted by cleszkie

In case anyone is interested, I have gotten my alt gauge to function with my one-wire alternator. Attached is the modified wiring diagram (thanks Vetvett for the original diagram) . Note that I have removed all of the original wiring associated with the external voltage regulator, and the original three-wire set-up.

I ran a Red 4 ga wire directly from the alternator to the battery. I did leave the original Red 12 ga wire from the fender junction block to the firewall harness to provide power to the cab wiring harness.

so what you are saying is that you are charging the battery with a 4 gauge wire and feeding the rest of the truck with a little 12 gauge wire. I think I would have done it the other way around. As long as you don't add a lot of amp draw loads it will be OK but if you add electrical fans or HD lights that little wire won't cut it.

]I basically just removed the Black/White 18 ga wire from the original wiring junction and ran it directly to the alternator. This way, the Alt gauge gets the battery voltage reading from the Black 18 ga wire on one side, and the alternator voltage reading from the Black/White 18 ga wire on the other side.

What you have done is to change the SHUNT wire from the 12 gauge red wire that runs across the front of the radiator to the main junction, to the 4 gauge wire that runs between the alternator and the battery. while it will still indicate charge, it won't be very accurate, not that they were very accurate anyway.

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The Alt gauge now registers the relative difference in voltages with the needle slightly to the charge side when the truck is running.