Trailer Lights Stopped Working on Wiring Harness # 118558 for 2013 Honda Pilot

Question:

Your unit 118558 installed last year on my 2013 Honda Pilot. Worked perfectly. This year went to use and no brake or blinker lights. Ground checked out ok and we could get power to the running lights. I went into the rear panel where I installed the control box last year and all seemed fine. I noticed on the aux access door it showed fuses but none could be located behind the panel. Could it be the control box or? Thanks

asked by: Bob W

Expert Reply:

Thank you for your September 2013 purchase of trailer wiring harness kit # 118558 for your 2013 Honda Pilot.

First, check that all of the relays are inserted properly in the harness and the fuse you installed in the engine compartment is still okay. You can also unplug the relays and connectors to inspect the condition of the contacts, looking for any dirt, potential corrosion from moisture or any other visible condition that could explain the non-functioning stop/turn lights.

If your 4-pole connector was exposed to the elements during the last year it may have a corrosion issue - even slight greenish or whitish discoloration on the 4-pole contacts can indicate corrosion sever enough to block proper signal transfer. Use a spray-on contact cleaner (available at most hardware and electronics stores) to remove any signs of corrosion.

If you have a circuit tester like # PTW2993 you can test the 4-pole (without the trailer connected) to see if the correct signals are present there. Please refer to the linked photo for the functions carried on each pin. The yellow and green wires carry, respectively, the left and right turn and stop light signals. Test the pins and also the wires leading into them; if you have signals on the wires but not the pins and cleaning them does not help, you can wire in a replacement 4-pole connector like # 118001. If the harness tests out okay, then repeat the inspection process on the trailer connector.

Repeat the inspection process on the trailer connector. You can also test the trailer directly by applying 12V power to each circuit on the trailer 4-pole connector. You can use the car's battery or a spare 12V battery. If the trailer lights work in this fashion, then the harness is likely to be the issue and should be replaced.