No Running Lights on Trailer

[RowMatt]

Good Day All
We are one week into a six month trip to warmer places. While traveling to Carrabelle Florida (Ho Hum RV park). While traveling here we lost our Running Lights on the trailer. Our running lights on the 2008 Ford 350 Diesel truck work fine. The electric Brakes and Brake lights work on the trailer.
I have connected 12V to the trailer plug and the running lights will work when voltage is applied.
It seems that the Truck does not provide 12V to proper pins on the Plug.
Does anyone know what fuse I should be looking at that would only supply voltage to the plug?? Remember the Truck Running lights work.

[Edd505]

Check for power at #4 Green if there is power check that mating connection in the trailer 7 way.

[Sundancer330]

I had a similar problem and found a pinched wire on the trailer that blew a fuse in the truck. Check your truck owners manual and look at the fuse diagram, there should be a fuse for trailer running lights.

[RowMatt]

Thanks EDD505
I have no voltage on pin #4. I have voltage on the left and right signal pins and 12volts Aux power. I need to know what fuse or relay controls the voltage to that pin #4 for the running lights.

[Sundancer330]

Looking online its fuse #42 which is under the hood that controls trailer running lights.

[RufusBC]

I had a similar problem on a Jeep Cherokee 2016.
Brake lights worked but running lights not so much.
Turns out when I have the lights on AUTO, running lights don't come on.
I just changed it to 'lights on' and there you have it, running lights all good.
Probably not your issue but definitely a Chrysler thing, I would think.

[Edd505]

Originally Posted by RowMatt

Thanks EDD505
I have no voltage on pin #4. I have voltage on the left and right signal pins and 12volts Aux power. I need to know what fuse or relay controls the voltage to that pin #4 for the running lights.

There is a fuse box under the hood on the lf fender and as I recall there you will find a fuse for the trailer and a diagram under the cover of fuse locations.
Found this and I think it matches your truck. To check the relay just swap it with another one in the box and if it works find an auto parts store - fixed.

[RowMatt]

It was Fuse #42. It is not easy to find under a vacuum pump on the driver's side. $5.00 for a new fuse and all ready to go. I will pick up a spare incase it happens again because I do not know what happen in the first place.
Yes if you are running your lights on move models of vehicles these days when the sun comes up it will turn off your running light.
Thanks again for your help.

Rhonda and Matt send.........Happy Trails

[jeffsr1999]

[QUOTE=RowMatt;465564]It was Fuse #42. It is not easy to find under a vacuum pump on the driver's side. $5.00 for a new fuse and all ready to go. I will pick up a spare incase it happens again because I do not know what happen in the first place.
Yes if you are running your lights on move models of vehicles these days when the sun comes up it will turn off your running light.
Thanks again for your help.

Rhonda and Matt send.........Happy Trails[/QUOTE

Thank you! On my 2011 F250 it was fuse #30 under the hood. I swapped it with the passenger seat fuse and the trailer was lit up!! Told my wife I hope she likes her seat position til we get home.

[Doug]

Originally Posted by Sundancer330

Looking online its fuse #42 which is under the hood that controls trailer running lights.

Good piece of information Sundancer.
Nice for folks to search information for people on the road.

Doug