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P0620. im confused!

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49K views 5 replies 7 participants last post by  hicksf350  
#1 ·
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!
 
#2 ·
The first thing that comes to muy mind is a bad connection. Maybe someone who has encountered this issue could help yo out.
 
#3 ·
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
 
#6 ·
had the same problem new alternator and 2 new batterys.kept getting a code 620 found out it a software problem if you don't use a ford motorcraft alternator the pcm cant connect to the voltage regulator that's what throws the code even thou the alternator it putting out the correct juice.i put in a ford motor craft alternator and the light went off.its how ford kept moving their parts ford parts for ford trucks after market alternators will give you a code 620 everytime.