2008 F150 5.4 super crew alternator went bad along with battery replaced both a few days later voltage meter going to high battery light on everything checks out Ok with volts it happens on and off a few more times replace alternator again still happening pull a code for alternator control circuit P0620 no check engine light or anything check the omhs to the control circuit get nothing anybody have any input on this I'm at a loss

 

Where did you get the alternator? Which output did you get? The regulators on our alternators are real easy to fry.

 

is it a motorcraft ?

 

Yes it is a motor craft re manufactured alternator

 

Update Che ked voltage with vehicle off battery was 12.38 turned vehicle on checked again 14.58 with no load turned on everything it dropped to 13.28 I'm inclined to say regulator anyone agree or have any other input

 

Yea I would say the regulator. I bought a remanned alternator and ended up having to buy a new one cause two remanned I got the regulator was burned up. Talked to a buddy who builds alternators and said ours couldn't be tested after a rebuild at the regulator cause of that issue.

 

I'm going to replaced the alternator for the third time I will let you know if that fixes it