Why do my 2008 F 350 Super Duty trailer lights not work?

if it has the plugin part that you can pull out-plug in,then hook trailor lights to,that is bad.can get a new one at any parts store.

just fixed the same problem on my exact same truck as yours. go to the fuse box that is under the hood on driver's side. there is a pump or vacuum switching valve sitting on top of fuse box. find the only 25 amp fuse in fuse box. that one is for trailer brake and blinker lights

F350 DRW here... Would that explain them working, then not working?? I am frustrated. My lights on my bumper pull were working today, then quit.. which would be a fuse right?? But then I plugged in my gooseneck and all running, etc. lights work on it. Any suggestions??

I have the same problem. when the obvious occurs, you figure: must be the fuse. I test the outlet to the trailer and there is no power (coincidentally, there are no license plate lights either). I tow the truck home with the trailer plugged in (and not working) park the truck , open the door, and suddenly, all the trailer lights come on! HOW could that be when I was testing the outlet, there was NO POWER? (and yes, I had the lights on, the flashers going, all that stuff) (and yes, my tester works). trucks are becoming like the darn space shuttle.

Thanks to toytech! I spent 6 hours at Camping World in Fife, WA last week waiting for them to diagnose and fix the problem with my 5th-wheel brake and turn signal lights not working. At one point they ran a bypass line from the truck to the rear of the trailer (which they later had to remove). As I was leaving ($240 poorer) one of the mechanics gave me a heads up that it was only a truck fuse all along. So much for my confidence in Camping World. Anyway, we reached our destination, but the same fuse blew again when we hooked up to come home. Thanks to you I got the replacement 25 amp and everything again works fine. I hope it was just a bad replacement fuse and not a systemic problem. Guess I'll find out next time out, in a couple weeks.

Same issue here. Had running lights but not turn/stop (on pickup trucks your turn and stop lights are on the same wire/circuit). Replaced the number 33 fuse (25amp) under the hood on the driver side. I hope this fix will last but I doubt it. I had similar issue on my 2004 f350. Just another ford wiring issue, I guess.

Many times when cleance lights are not working on truck and trailer with other lights still functional you have a faulty head lamp switch. I found this to be the problem with my 2006 f350 super duty.

Inadvertantly grounded a new side running light on my trailer which caused fuses 33 and 42 in the engine compartment fuse box of my 2008 Ford F-350 to blow. 33 runs the brake and turn signal lights, 42 runs the running lights. Took an afternoon to figure it out, the owner's manual does not show what these fuses are for.

Under your traikler is a ground bar might sure its clean to make a good ground $100 to learn that lesson