alternator idiot light won't go out

I have an ASV rc 100 with 2700 hours. The alternator/battery light always stays on when the machine is running. The alternator is new and putting out 14+ volts. prior owner has a pigtailed wire on the battery lead near the alternator that attaches to nothing. I'm trying to figure out why the idiot light won't go out once the rig is running. Of course the light is off until the key is switched on . any help or suggestions would be appreciated

A typical alternator field circuit is a low resistance circuit when not spinning and fielded. This field current usually comes in paralell through the bulb and a resistor. When the field is energized, current drops off and the bulb seems to go out. Bulb can stay lit if there's a short in the harness or in more modern alternators, the regulator can light the bulb. Check for AC voltage on the line, maybe its a bad diode.