Charging System Question

Early regulators are basically a normally closed relay contact between IGN and FLD. Coil of relay is on IGN and ground. When the IGN voltage is about 13.8V, the NC contact opens cutting field. After a short time voltage drops, and NC contacts close again, then open as voltage hits 13.8V, chattering as necessary to maintain voltage. If ground is lost at regulator, relay coil never sees voltage, IGN to FLD contact stays shut, so voltage runs high, and will cook battery.

Shorting FLD to ground on a good regulator, may weld regulator contact, or burn up IGN circuit wiring.