[davem815]

'70 GMC 307 with external voltage regulator and optional gauges in the dash cluster.

Truck quit charging, dies if I remove positive battery terminal
It has ran fine for a year and a half. PO replaced alternator within a year of selling truck to me. I had alternator checked at an alternator/starter shop and it tested fine. I replaced EVR. No change.

I have no voltage at F terminal of EVR with or without engine running. Amp gauge on dash points straight up (half way between D and C) with or without engine running. If I jump 12v from battery to F terminal on EVR, amp gauge goes to 3/4 Mark (toward C).

My research says F terminal should have around 3-4 volts with key on, engine off and 12-14 volts with engine running. I followed blue and Brown wires from alternator to EVR to firewall and did not see any breaks or splices.

What could cause no voltage at F terminal?

Thanks in advance for your help, Dave