Help me out here because this is right in the middle of when Ford was switching to a pretty decent generator design. It sounds like you have the gray voltage regulator bolted to the back of the generator with four screws. Is that right? If so, there's two additional screws near the bottom, and one has a "Ground here to test" message printed next to it. Grounding that terminal will bypass the voltage regulator. If that makes it charge wide-open, the regulator is defective and can be replaced separately. If it still doesn't charge, either the brushes are worn or you're missing the 12 volt field supply voltage that comes in on the yellow wire. The second, unmarked test terminal, which may have a plastic cap on it, must have 12 volts all the time. If that is missing, you have a blown 15 amp fuse.
If grounding the test terminal makes the generator work, you also must check if the "turn-on" circuit is working. That's the green wire and it comes from the "Battery" light on the dash. If the Battery light turns on when you turn on the ignition switch, AND it goes off if you unplug the three-wire plug at the regulator / generator, that circuit is working. If the Battery light never turns on, we have to test further to see if the bulb is burned out or there's a break in that wire. The circuit will still operate if the bulb is burned out because there's also a resistor across the bulb socket in case that happens. If the light stays on when the regulator is unplugged, that green wire is grounded, and the voltage will never appear at the regulator to tell it to turn on.
Saturday, March 22nd, 2014 AT 1:50 PM