2003 Hemi Ram battery gauge went to zero coming home from work, lights got dim, but made it home. Parked it, and couple days later gauge was back to normal for a minute or so then back down to zero. Checked voltage at battery and it fluctuates from zero to 15 then settles in at 11.8v. I replaced alternator today and same thing. I've seen several people with same issue but haven't found any answers. Can anyone help me that may have experienced this before? My next step is to replace PCM. Any help is greatly appreciated.

 

its showing code p0622

 

Sorry,but I don't have a solution for you.The code in my shop manual however reads:

P0622-Alternator field circuit not switching correctly

 

check battery cables. both positive and negative... and all ends are clean.. and no rust at the body ends... poor connections is most likely the issue...

floating grounds.... are BAD..