Check charging system

[jeffsk8r6]

I need assistance. I have the battery light on in the truck and has been for a good minute now. I don’t know what to do. I have a good voltage reading on the battery, alternator, and all the wires. I replaced the alternator pigtail figuring it would fix it because the battery, alternator, starter, tensioner pulley, and belt have been replaced to no avail for the light coming on. Even after you clear it the light comes back every 20 min or so. Anything I could be missing here? I am stumped.

Also the new pigtail was 3 wire but stock was 2 what do I need to do with the 3rd wire or is it pointless

 

[Todd Z]

Sounds like there is a bad diode pattern in the alternator, bench tests and volts will not tell you that.
Could be a cluster issue too..... But a ford scan tool may be needed. BUT I say replace the alternator.