Trailer Works with One vehicle But Not Another  

2105 Honda Accord Coupe with Curt Custom Fit Vehicle Wiring part# C56011. Trailer works fine with a different vehicle 2008 Vibe, but not with Accord. Accord wiring mostly works with a different trailer. With that other trailer all lights work except the right brake light when the car is not running. All lights work when car is running When I hook up the Accord and the problem trailer, running lights work but brakes and turn signals mostly dont. Occasionally brakes and turn signals will work briefly for a minute then inexplicably stops again. Sounds like a ground problem, right? Ground connection on both car end and trailer end sanded down to bare metal. Sanded plug prongs too. When that didnt work I ran ground wires directly to each tail light, no dice. Multimeter test shows 0.2 ohms same as when you touch the two multimeter probes together on all legs of the ground wire bare metal car to bare metal trailer, car ground nut to trailer ground nut, car ground nut to ground bolt on tail light, trailer ground to ground bolt on tail light, etc. Even ran jumper cables from car ground nut to trail ground nut and then lights ground bolt, still nothing. No scrapes or pinches in the wire insulation I can find. Voltage at 4 way plug is 13.4V for turn signals, 12.6V for brakes, which is the same as the other car so I assume thats right. Im out of ideas. Faulty wiring harness maybe? But then why does it work mostly with the other trailer?

asked by: Bob F