denkath wrote: 1999 Tarus 3.0 L,
The alt light comes on only on hard acceleration.
Could be worn alternator brushes. You can buy brushes
at auto parts stores about $15-$25, open the alternator
and replace them. While the alternator is open,clean
any corrosion or contamination on the slip-rings using fine
emery/sandpaper & alcohol.
Sometimes dirty slip-rings can be cleaned without opening
the alternator by sticking a pencil eraser into the back to
clean the brush tracks while turning the pulley by hand.
Wendy & John.