I always use WD40 to spray into the 7-pin socket and move it all around to clean the contacts... I think we all have a can of WD40 and some DUCT TAPE on board... Even some bailing wire haha...
Never leave home without them haha...
Since you have replaced the 7-way connector it must be a ground or something not right with the leads feeding the rear hookup.
My truck has the DUAL 7-way and four way trailer connector as a unit with spring door that is used for locking into the trailer plug...
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Roy Ken
My Posts are IMHO based on my experiences - Words in CAPS does not mean I am shouting
Roy - Carolyn
RETIRED DOAF/DON/DOD/CONTR RADIO TECH (42yrs)
K9PHT (Since 1957) 146.52M
2010 F150, 5.4,3:73 Gears,SCab
2008 Starcraft 14RT EU2000i GEN
2005 Flagstaff 8528RESS