Non Mopar alternator question

The one you applied 12v to & got 13.8v out of it should get power with the key on. With the engine running & voltage applied, check for voltage coming OUT of the other terminal. This is for the charging system light and should get connected to the circuit accordingly.

The charging system light comes on when there is NO voltage coming out of the terminal. The bulb is wired positive with Ignition on 1 side & the other is grounded. Also connecting to the ground side of the bulb is the wire coming from the alternator. When there is no voltage form the alternator the bulb is on. When the alternator starts producing voltage on that wire it takes away the ground & the bulb goes out because you cant have a circuit with 2 positive sides on the bulb(or any component).