Truck lights work trailer don't
Have a 99 ford 350 all of my lights on truck work
but when I hook.up to my trailer nothing works on
the trailer. Have changed the wire harness and
connection plug. Any fuse suggestions
With lights on have you checked with voltmeter to insure there is power to the plug?
Sounds like your missing a ground. Make sure power and ground wires are hooked up correctly to the trailers wiring.