Originally Posted by fordborn
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!
Check the operation of the charging system warning indicator in the instrument cluster (IC) as follows:
With the key in the OFF position, the charging system warning indicator should be off.
With the key in the ON position and the engine off, the charging system warning indicator should be on.
With the engine running, the charging system warning indicator should be off.
NOTE: The PCM requires 3 key cycles to re-learn the configuration.
P0620 Primary Generator Control Circuit PCM
did you check Check : Fusible link SDC02. sometimes they burn up when it fries