Troubleshooting Trailer Running Lights that Stay On After Installing Brake Controller

Question:

When I hooked my Reece pilot trailer brake controller up, everything works perfect except the running lights stay on on just the trailer even when the truck is completely off with no lights on on the truck.

asked by: Steven H

Expert Reply:

If the running lights on your trailer are staying on, even with the tow vehicle off, it's possible that the trailer connector is mis-wired. I recommend first using a circuit tester like # PTW2993 to test the pins on the vehicle side connector. Make sure that there is no power at the running lights circuit when the vehicle and lights are turned off. If you do not have power there, then we know the issue is somewhere on the trailer side.

On the trailer side, I recommend checking its 7-Way connector to make sure the running lights wire isn't attached to the 12V power pin inside the connector. Check the connectors inside the trailer end and make sure each one is properly wired and not shorted between two points. Look specifically at the brown wire (tail lights) and black wire (12V), as they are next to each other on a 7-Way so it can be easy to make the wrong connection. You can use the attached image for reference.

If the connector itself is wired properly, I recommend checking the wiring along the trailer to make sure there are no exposed areas of wiring that might be making contact with each other, fixing as needed.

If you are still unable to resolve the issue, please let me know and I will be happy to look into this further.

expert reply by: Chris R