Amp light works backwards

The amp light on my 71 CJ V6 is working backwards. That is, when the ignition is turned to the on position (engine not running) the light does not come on. When I start the enigine. The light comes on. The alternator is putting out 14+ volts, so I don't see how the light would be on when the alternator is charging, but off when it is not charging. It's the opposite of what is supposed to do!!!

I don't know much about wiring and electricity, and I've searched the forum and read everything about the amp light that i could find, but I still can't figure it out. Can anyone help???

 

The ignition side of the alt bulb is somehow grounded.

Usually the amp light goes from the ignition switch, to the light, and to the "exciter" terminal on the alternator. With the alternator not turning, the exciter wire sinks current and the bulb lights. Once the alternator starts producing current, the exciter wire goes to the charging voltage. With full voltage at both sides of the bulb, the light goes off.

You can see how, if the switch side of the bulb were grounded, the bulb will be off when the alternator is not charging, and vice versa.

 

I wondered where that green wire was upposed to go! With your guidance I connected it to the ignition switch and the light works as designed! I've been messing with this for a couple of days between pulling the dash out, and searching the forum for help. I guarantee I'll never forget this one! THANKS A MILLION.

 

Glad I could help!