Electrical problem
1990 Mercury Marquis V8 Two Wheel Drive Automatic 80,000 miles

there is a 14-16 ga. green wire with a red stripe coming from the small plug in the alternator that was cut and I cannot find where to terminate it. It has made the charging system not work. what is the function of this wire and where do I terminate it.?
I found a simular colored wire coming out of the brain , but am hesitant to splice into it for fear of shorting the alternator.