alright yall heres the story. last weekend my alternator fryed. just gave out. got a Job 1 6.4 powerstroke. so i put in a new, 200 amp alternator. its a single alternator, dual battery set up. now my battery light is on and the P0620 code has been set. even when i clear it, it ends up coming back. the code is for a generator control circuit malfunction. my alternator is charging at 14.2 volts steady. runs fine. no humming or weird noises. before i started working on it i checked my battery voltages. they were both at zero. dead as a doorknob. but their holding a charge fine now. i dont understand what this code means, ALLDATA and Mitchell dont say ****. going to talk to a ford commercial tech now, just wanted to see what yall had to say. thanks guys!