on my 06 fx4 i have the factory tow package. prevous owner put a trailer brake controller on it.i rewired my grandpas trailer with a new light kit.went to take trailer back and brake lights and flashers worked on trailer but the lights them selves didnt work.my dad checked the round plug and the 4 flat and neither one works.do i start at brake controller under dash or just run single wire from plug and tie it in at light switch.any ideas would help greatly.thanks

 

If your talking abt the running lights, that would have anything to do with the brake controller. Check all your grounds, always start at the trailer.

 

Also check your trailer light fuse. Ive blown mine a couple times.

 

thanks. will do.yes its the running lights that dont work but brake and turn signals still work on trailer.dad checked plugs with volt meter and im not getting power to plug for running lights.everything else works.

 

It's a fuse in the truck a 20 amp. I had the same problem

 

thanks.is it the fuse box hidden on passenger side.i found it when i had my cruise issue

 

Yes. I think I ended up replacing 2 fuses when I replaced my trailer hitch adapter.

 

Yes. If I recall its near the bottom left side a green 20 amp. You can by a box of 5 for a couple bucks. Left meaning toward the front of the truck

 

Also if your fuses aren't blown then always check right behind the plug where the wires connect to the plug... you might have a bad plug..

 

there are 4 fuses i think for our trucks towing adapters, check the manual if you got it one is a real pain to get to, pulling the relay out of they way makes it a ton easier.

They have a plug in tester at harbor freight if you have one near you, for like 3 bucks.Lots easier to use than a meter and I use one everday being an electrician. Keep it in my truck box so when soemone els has a problem you can help elemintae truck or trailer in seconds.