Recently purchased a used unit from General RV in Wixom, MI.  The 6V lead acid batteries were not cared for and I replaced them with 4 AGM style units.  I have an extra cable, labeled 'D' that is folded up to the top of the bay against the forward bay wall.  I didn't see or chart it during the batteries extraction process, and do not know where to connect it.  Does anyone have any idea which post it "belongs to"?  Thank you in advance.   Mark