Truck/Traiiler Wiring Question

[Tigerbdog]

I have a 2019 F-250 work truck and at least four different trailers I pull. The turn signals, brake lights, and caution lights work on each trailer when connected to the truck but they are not illuminated when driving. Three are seven pin and one is four. I've been slammed and haven't had time to research this. Is it as simple as a blown fuse or is there a wiring issue with the truck?

[Budman-08]

Find the fuse that is your trailer running lights.

[Fireman]

If they work before the trailer is connected to the ball you may have a ground issue. A quick way to test is to buy one of the "trailer light testers" from somewhere like northern tool. Plug it in to the truck and go through all the differenet ones. It will tell you if its a truck issue, or an issue in the trailer. My money would be on a ground issue somewhere though.

[centurian]

If you have the round 7 pin plug in it may be as simple as jiggling the plug. I have a similar problem with the running lights and sometime the left turn signal. If i turn the plug in a little to the right it seemz to work fine until the next time. I have a new heavy duty plug on my desk to install when i get a chance after deer season. If it never works it may be the fuse for the trailer running lights as mentioned above.

[BigBrother]

Look behind the bumper to where your wires plug into the back of the bumper piece (technical name escapes me). Make sure you havent pulled one out.

[WoodieSC]

The easiest check is to see if your headlight switch is on ‘Auto’ vs ‘On’. I discovered years ago that if I forgot to change the switch setting the running lights wouldn’t work in ‘Auto’.

[FishSticker]

Check whether you have center pin or top pin ground...