External regulator conversion question

Common problem and I have read on Dodge truck forums where others have tapped the factory wires to install an external 1970's Vreg. Search for those. They might also tell how to make the CEL turn off. My 1996 Voyager is similar, w/ the Vreg integral w/ the Power Control Module (PCM). I recall it uses the same circuit as a 1970's Mopar, one field +IGN and the downstream field going to a transistor (low-side control). The circuit is fairly independent of the rest of the PCM, it was just cheaper to package it there, plus whatever wiring might be for the check function.