guys, whats the deal with my 7 wire electrical connector ...the one near my hitch reciever below my rear bumpa???when i plug in my wire from my 14000 lb flatbed, my lites go nuts ?? tks in advance for your help...2003 silverado

I have seen this before - it sounds like the trailer harness is shorted. There are testing units out there to test the trailer system and tell you what the problem is. You could test your truck system by plugging in you Jayco or another trailer you know is correct.