2017 Ford F250 Super Duty 6.7 turbo.
Renting this truck to pull an enclosed trailer. I connected the trailer to the truck and only have running lights on the trailer. Turn signals and brake lights work on the truck but not on the trailer. I checked power to the terminals on the 7 way plug and 4 way flat plug. I am only getting power to running lights on both plugs. I checked fuse 72, it is for trailer tow left/right/stop/turn. It is good. I also checked other trailer tow fuses 42, 54, 65, 84, and 99. They are all good. I checked them with a test light. I checked the wires under the truck and all seems good.
Do these trucks come ready to tow or does it need something else to make the turn and brake lights work? Another harness, relay, programmed?
Thanks,
Kirk

 

While I've never had this exact issue, you might try setting the parking brake, then with your foot on the brake, put it in neutral, and give it another try. When I hook my TT, I can leave it in park and it works. I test lights with the parking lights on, and emergency flashers. That activate all elements. Also try wiggling the plug around in the socket. There are fuses under the hood for the trailer lights.

 

Try the trailer on another truck just to rule out that the truck is the problem. Based on what you posted it sounds like the trailer has wiring issues.

Are you going to be using a 7 pin or 4 pin plug?

 

Didn't have another truck to hook trailer. I did connect a battery to trailer plug to test the lights. Battery negative to trailer plug negative. Then to running lights, left turn, and right turn on plug. All lights on trailer are working correctly.

 

From your description, it seems (to me) there is a break in the stop and turn wires between the fuse box and the rear of the truck. This needs checked, (hopefully) by the person or company that rented you the truck....

 

Thanks for all suggestions. I ended up taking the truck back to renter. Weather turned bad so I just turned it in.
Thanks,
Kirk