Re: Non working trailer lights
About 95% of trailer light problems are bad grounds. I always use a battery at the coupler to test the wiring on the trailer and connect the negative battery lug to the trailer chassis. See what's working. You can test the wiring with a meter for continuity, and use the meter to check for 12 volts at the sockets. Don't rely on a ground to transfer through the hitch to the trailer. It should be in the pigtail connector.
