Troubleshooting Running Lights Not Working with 2005 Ford F-150

Question:

i have brake lights on my trailor and turn signals , but i do not have running lights on them and they seem dim when i press the brakes

asked by: Jeremy C

Expert Reply:

It sounds like there may be a bad or weak ground connection on your F-150 wiring or the wiring on the trailer.

What I first recommend doing is testing the 7-Way connector on your Ford F-150 with a circuit tester like # PTW2993. Test the running lights pin (11 o'clock position) on the 7-Way with the running lights activated on the truck. If you get power, then the issue is actually on the trailer side.

Check the ground connections on your trailer and make sure they are all secured to clean, bare metal surfaces on the frame. You can also try inspecting the running lights wire to make sure there are no exposed or damaged sections that need to be replaced. Then take a look at the 7-Way itself on both the trailer and truck for any debris or corrosion that needs to be cleaned out.

If you did not get power at the truck's 7-Way when testing it then you know the issue is on the truck. In this case I recommend checking the 20 amp mini fuse that should be located in the # 10 position inside the passenger compartment fuse panel. This fuse is for the trailer running lights.

If you are still unable to resolve the issue please let me know and we can continue to troubleshoot.

expert reply by: Chris R