Troubleshooting a Utility Trailer with Newly Rewired Taillights that Are Not Functioning

Published 03/18/2014

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16 Gauge, 4 Conductor Bonded Parallel Wire - Per Foot

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Hook Probe Circuit Tester

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Question:

I recently bought a harbor freight 4foot X4foot trailer, I have a 2007 dodge nitro with the factory installed trailer outlet. I ran the wiring according to the diagram and the only lights that work are the side maker lights. when I turn on the directionals to the left or the right they both blink. Still no power for tail lights.

asked by: Bud

Expert Reply:

It sounds like the problem is in the wiring of the trailer since the wiring on your vehicle is from the factory and you just wired up the trailer. But just to rule out your 2007 Dodge Nitro as the problem you could use a circuit tester like part # PTW2993 and test the circuits of the trailer connector on your vehicle while someone applies the various turn signals. Check out the video I attached that shows how to do this.

It really sounds like you have the wiring messed up on the trailer. I would recommend you trace the wiring from the 4-way on your trailer back to the tail lights and the side marker lights and make sure you only have the running light circuit run to your side marker lights and the stop/turn circuits are run to the taillights. As well as the running lights to the taillights accordingly. I attached a diagram that has how a trailer normally gets wired depicted.

You also want to be sure that the taillight assemblies are grounded well. If the assemblies ground through the mounting hardware then you will need to make sure they are attached to a clean metal surface.

I attached an FAQ article on troubleshooting 4-way installs for you to check out as well that might be helpful.

expert reply by: Jameson C