Troubleshooting Vehicle Wiring Harness On 2011 Honda Pilot Not Powering Trailer Running Lights

Updated 07/30/2021 | Published 07/28/2021

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Question:

I have brake and turning signal lights, but no running lights on my trailer. If I hook to someone else’s vehicle everything works. I’ve replaced the wiring whip under the truck with a new part consisting of the modular plug in, and the wiring to a 4 pin connector, all new as one unit, same result. I’ve checked fuses in the rear Pilot panel, and all are good. Aaaaaaargh!

asked by: Frank F

Expert Reply:

I am sorry to hear about the issue you are having getting the running lights on your trailer to work when being towed with your 2011 Honda Pilot.

Since you have checked the fuses in the rear fuse block, I recommend checking the fuse you installed in the engine bay fuse block as well to make sure it is still good and is fully seated.

If that checks out, I recommend using a circuit tester # PTW2993 to test the brown wire of your 4-way harness while the head lights of your Pilot are turned on. If you do not have any power on that wire, then remove the 4-way connector harness and double check that no pins in the factory connector are bent causing power to not make its way into the harness.

If that all checks out then test each wire going into the module near to see if it has power when the headlights are turned on, and then turn off the headlights to verify that the specific wire does not have power now. The correct wire will only have power when the headlights are turned on.

Let me know what you find, and we can go into more in-depth troubleshooting if needed.

expert reply by: Samuel C