I just went through this with my taurus SHO. I was told it was the alternator going out. You can't do a test at the battery if the light isn't always on. Autozone will test the aternator, but I suggest you go to the ford dealer. Mine almost cost me $500 in parts and labor, but it turned out it was just a loose wire that costed me $35 for a diagnostic check.
Good luck !
Thursday, April 20th, 2006 AT 9:09 PM