I have a 2001 f-150 5.4 v8. all the lights on the truck work fine, but when I try to run trailer lights things get a little crazy. I have blinkers but both flash at the same time no matter which side I flip to. Then at night when the headlights are on the trailer lights will work, but if I hit the brake all trailer lights go out. also no blinkers. Please help! Thanks

 

Have you checked your wiring at the plug?

 

Make sure all your connections are clean, also try n hook the trailer up to a friends truck to ensure the trailer is wired properly...

 

Another thing if u look under truck where the wires come in the back of the wire harness they sometimes get loose or tore up from dirt snow and what not

 

thanks ill give that a try.