Troubleshooting Trailer Running Lamp Circuit on Camper Towed By 2013 Honda Pilot  

Question:

Expert Reply:

The first thing to determine is if the problem exists on the tow vehicle or on the trailer. Turn on the vehicle headlights and use a circuit tester like # PTW2993. For a 7-way trailer connector, the pin in the 11:00 position should show voltage with the vehicle headlights or running lights on. (Make sure those are on, and not the daytime running lights, and also make sure that the headlights are actually switched on, and that you're not relying on an 'Auto' lamp setting). For a 4-pole trailer connector, the pin fed by the brown wire should show voltage.

If you do see voltage on that pin, the problem is in the running lamp circuit on the trailer. Trace the running lamp circuit from the connector back to the taillights looking for broken wires or loose connections. Repair as needed.

If you see no voltage on the described pins, you likely have a blown fuse. Check the fuses in the sub-panel in the engine compartment next to the battery. The lid of the fuse box should list the fuse locations. If you find a blown fuse, you can replace it, but do NOT plug the trailer back in until you can go over the running lamp circuit on the trailer to find and repair the short that caused the fuse to blow, or you'll continue blowing fuses. Begin at the trailer connector, make sure it's not corroded or damaged. Trace the running lamp circuit back to the rear of the trailer, looking for loose connections, pinched or scorched wires or wires with worn or cracked insulation that would allow the copper core of the wire to short out on the trailer frame.

These are all the common suspects. I'll also link to a help article with additional troubleshooting strategies.

expert reply by: Mike L

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