I have 2018 Sprinter motor home. I blew a fuse under sprinter seat to trailer (jeep). Replaced fuse and checked all fuses but no lights. Installed new outlet and new whip. I plug in the tester light to seven blade outlet and everything shows good. Signal lights, brake lights, tail lights all show to be working but plug in the new connector and nothing tests out with test light. I am at the end of my wits.