Re: no brake or turn signal
After many years of chasing the same kind of "ghosts" the OP is reporting, I gave up on trailer frame grounds and ran a ground wire to each trailer light from the connector and guess what? No more lighting issues or problems!
If it absolutely makes no sense and acts like magic; you have a ground problem!
After many years of chasing the same kind of "ghosts" the OP is reporting, I gave up on trailer frame grounds and ran a ground wire to each trailer light from the connector and guess what? No more lighting issues or problems!