We have a 980 F Series II, can't quite recall the manufactured year though. It has a 30,000 plus hours on it, but has been a good running machine. A few weeks ago the battery light started to flash, first thing we checked were the ALT belts, tightened them up and it kept flashing. Next day ordered a new alternator and put it in, light still flashes. Weeks go by and it is still flashing, but is running fine, no lights dimming. Does any one have any other things to look at that could cause the warning light? Is it just faulty?
Check the wire coming from the "R" terminal on the alternator. It is the one that will cause the light to come on if there is no current.