Troubleshooting Running Lamp Circuit on Trailer Towed by 2011 Ford Super Duty Truck

Question:

I just purchased a 2011 ford superduty , I plugged my horse trailer in to the plug I have turn and brake lights and the brakes work , but I have no running lights, the trailer lights were working on my 2002 ford powerstroke , I checked the relay and the fuse they seem to be good ,

asked by: Kim P

Expert Reply:

If you haven't done so already, you'll want to use a circuit tester like part # PTW2993 on the running light pin on your trailer connector, which would be the pin in the 11:00 position.

If you get power on that pin when the running lamps on the vehicle is switched on, the problem is in the trailer wiring. You'd need to trace the running lamp circuit on the trailer, looking for pinched or broken wires or loose connections.

If you don't get power on that pin, make sure you checked the trailer running lamp fuse, and not the truck running lamp fuse. If the fuse checks out okay, make sure he 7-way connector on the vehicle isn't damaged or excessively corroded. If you can see any corrosion on the pins of the 7-way, there's a chance that the corrosion has spread to the interior of the connector and is preventing the signal from getting through.

I'll link you to our trailer connector troubleshooting FAQ articles.

expert reply by: Mike L