I've recently started having issues with my trailer lights while pulling the boat. All of a sudden the parking lights have stopped working on the trailer. The break lights and turn signals are fine. I checked the fuses in the truck, and apparently there is a relay that controls the parking lights on the trailer. Is there a way to test the relay to see if that is really the problem?

 

I had this exact problem last summer with my boat trailer. Then found out no trailer had them when attached. Then found out I also had no reverse lights. I'd imagine you have the same problem. It was just a simple burnt fuse (caused by launching the boat I'm sure). Should get you fixed right up.

Here's the link that had the correct fuse numbers. Mine happened to be fuse #10

https://www.f150online.com/forums/sh...highlight=fuse

 

Thanks for the reply. I didnt notice if the reverse lights were working or not, I'll check that and the fuses this evening. In the owners manual it appears that there is reley for the trailer parking lights, could that have went bad as well?

 

It's always possible that the relay went bad. But, I'd bet it's just a fuse. Of course I could also be wrong.

 

Ive blown it a few times as well....in the diagram in the manual it does say and show the bigger relay fuse...but its not. There are 2 fuses together on the far back side next to the relays and its the top one of the 2...#10...

If you need a picture i can get one.

 

My '04 F150 lost the turn signals on the left side before I traded it. I thought the bulb was bad, but when I got the new truck, the left signal on my trailer worked again. I guess the new owner can worry about that.

 

One note that no-one seems to have realized is that the towing relay only controls the 30 amp charging circuit going out to the trailer. I towed my trailer with my dad's 04 and my 06 without the relay installed and all of my signals worked including my reverse lights on my trailer.

Besides fuses, grounds often cause problems with trailer circuits. Make certain you have a good ground set up on the trailer side so that you get good connections. Sometimes you can cheat and get a ground path through the ball, but that is not thebest way to go.