Troubleshooting Trailer Running Lights Not Working on Factory 4-Way For 2013 Ford F-150  

Question:

Expert Reply:

It sounds like you have done most of the troubleshooting already! You have ruled out the fuses/relays being the problem and by testing the 4-Way on the F-150 and seeing that you aren't getting power at the running lights pin, you also know that the trailer isn't an issue.

At this point the problem has to either be coming from the actual factory wiring between the running lights circuit and the 4-Way, or with the 4-Way connector itself. Since testing/inspecting the factory wiring will be awfully tough on your own, I recommend checking first to see if it's just a bad connector.

You can test this pretty easily by testing the running lights wire just behind the 4-Way with those lights activated on the truck. If you get power there, then you know it's stopping inside the connector. If this is the case you can just cut it off and replace it with a new 4-Way like the Hopkins endurance # HM48190.

If you didn't get power when testing the wiring behind the factory 4-Way, then there's a problem with the factory wiring along the truck. This is going to be pretty difficult to gain access to so your best option for actually finding and resolving the issue would be to bring the truck up to a local Ford dealer to have them take a look.

If you'd rather not do this (which is certainly understandable....) another option would be to simply install a new aftermarket 4-Way harness that would bypass the factory trailer wiring completely. To do this you can use the Tekonsha 4-Pole Hardwire Kit # 18252.

You will use the included quick-splice connectors and circuit tester to connect the 4-Way leads to the correct tail light circuit wires on the truck. I have attached the written install manual below that you can check out as well.

expert reply by: Chris R

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