Battery light stays on
I recently purchased a 2003 f150 and it
wasnt charging so bench tested alternator
and battery - both are good, cleaned all
connections replaced fusible link but the
thing still is not charging. I have looked for
the mega fuse without luck.
Any ideas would be greatly appreciated
So you either have a broken wire in the exciter circuit for the alternator or the computer is just not turning on the charging system, I have seen a few GM models do this but not any Fords, but anytime they involve a computer in a system that has worked fine for decades it really messes things up, so if it is not wiring related then your going to need to have the rig "live data" scanned to see if it is a computer failure.
The PCM may control the charging of the battery by the alternator. If that is the problem it will have to be diagnosed by a person who has the ability to read the outputs and signals generated by the PCM, utilizing a laptop with the correct program to read your particular year, make, and model vehicle.