1999 Ford Windstar

Electrical problem
1999 Ford Windstar 6 cyl Front Wheel Drive Automatic

The alternator light was coming on some times on my father in-laws 99 Windstar and I checked the voltage output and it was moving from 12+ to 13, so I replaced it with a remanufactured one that I got from AutoZone, But now the light stays on all the time and the output is over 14V. I found a article that said that this could happen if you don’t use a factory ford alternator. Is this true and how can I get the light to go out
May 17, 2010.

Check fuse no.20 15amp and fuse no.16 10amp if okay have the computer controlled of the alternator field generation circuit checked out-

May 17, 2010.