Help....My trailer brake lights and turn signals don't work. I checked the fuses inside and under the hood and there all fine. Is there something else I should check??
- The tail lamps are the only thing that will come on, on the trailer.
- I have this same problem with two different trailers.

Thanks for any input.

 

Check for lose wires at your conectors.

 

Did you check the 3rd small fuse box that is closest to the fire wall and is not mentioned in your owners manual??????

 

Is there more than 2 fuse boxes in the engine bay?? (don't have my truck at work)
I checked the one with approx. 12 small fused and 8 or so large type fuses, and I opened up 1 fuse box with what appears to be relays (small square fittings)

 

Check for corrosion on the truck plug. I have a 7-pole connector and with 97K miles including towing a snowmobile trailer, the connector needed replacing. Not a big deal, $5 for the connector unit and about an hour of time. You can clean them, but once the corrosion starts, its hard to get rid of.

 

Check the ground wire, it can make lights work oddly.


Rick

 

I had the same problem on my F150 it was the 7 pin harness on the truck itself. if you crawl under your truck and look at the backside of the harness you will probably see alot of corosion try to clean it off, if that doesn't remedy the problem you will probably have to replace the harness.

Good Luck.