How do you wire a 7 pole flat to a 6 pole round RV plug?
If the vehicle harness was wired correctly to start with you may
be able to buy an adapter from 7 flat to 6 round from the HOPPY
company. Otherwise buy a circuit tester and install a 6 pole round
pigtail connector on your harness using 3M scotchlok connectors.
This will allow you to keep your original flat 7 connector too.