1966 Voltage Regulators?

A simple test is done using a bench top power supply with adjustable voltage, 3A or more current capability, a voltmeter and 12 volt bulb. The bulb is placed on the regulator FLD terminal, the other terminal on ground (regulator case). The power supply (+) is connected to regulator IGN, (-) to regulator case.

Test as follows: Use meter to monitor voltage at IGN to regulator case. Set supply voltage to 12V, the bulb, should be lit, increase voltage slowly, the bulb will go out when the voltage is increased to regulating point, typically a few tenths around 13.8V. The bulb should turn back on as voltage is reduced, a bit below the regulating point.

For new two field terminal regulators, the bulb is connected from FLD terminal to (+) power supply, not ground as in early regulator test.