2017 F450 with factory dual alternators. Started getting the above warning a while ago but was so sporadic that was hard to diagnose. Various tests including battery voltage, charging amps, etc., finally indicated main 220 amp alternator was not charging. Replaced with OEM unit but the warning and battery light still illuminated. Returned to dealer where parts man suggested could be chaffed control wire between PCM and main alternator. He stated this was an issue on some of the '16s and earlier models but had no further details. Does anyone have wiring diagram/color codes that I can use to further diagnose this problem?