My 2003 5.4 was throwing up the battery light on the instrument cluster with a "Check Charging System" in the message center.
The light would randomly come on and go out.
Yesterday the light came on, and stayed on.
Also threw a CODE P0620 into the computer.
I did the Ohm reading test, and instead of 1.2 - 1.6 ohms as suggested by the previous article Part I, the Ohms were read at 960. So Sum Tin Wong so to speak.
I also have replaced the alternator and battery and alternator cable as per a Ford TSB on this subject.
Two of the alternators that I replaced were bad out of the box.
Third one from NAPA (Gold) worked for a while, and now the above. Going back in to NAPA to exchange and try again today.
I seem to be following the pattern from the Story Part 1 and Part 2.
Can't believe that it is that hard to get a decent rebuilt alternator.