Troubleshooting Trailer Turn Signals and Brake Lights Not Working When Connected To 2011 Ford F-250

Question:

I have a Ranger Trail boat trailer. Works fine on 2019 F150. When I hook up to 2011 F250, trailer parking lights will come on but nothing else. When I turn on parking and/or headlights, trailer running lights comes on, brake lights come on without pressing brake and no signal lights. I cut white wire on truck pig tail and ran to chassis hoping for a better ground. No change Murphys Law If you have any suggestions, they would be GREATLY appreciated.

asked by: Garry T

Expert Reply:

You are correct in assuming that the issue with the lights is more than likely a ground, do to how oddly the lights on your Ranger Boat Trailer are behaving when plugged into your 2011 Ford F-250, but since you already replaced the ground let's check a few other things.

Since the turn signals and brake lights are not coming on correct, I recommend using a circuit tester like the # PTW2993 to test the connector on your truck. Since you pretty well eliminated a ground issue, it is likely that there is another underlying issue. If you are not getting power to the turn signal/brake pins, then I recommend checking the engine compartment fuse box and making sure fuse number 100 is installed. It should be a 25-amp fuse and controls the turn signals.

Based on the issues you are having; this is likely your problem.

I included a link to a helpful article on wiring for you to take a look at.

expert reply by: Samuel C