Troubleshooting Turn Signals and Brake Lights Working on the Trailer but No Tail Lights Work

Updated 03/19/2024 | Published 03/18/2024

Products Featured in This Question

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(80)

$73.46

Hook Probe Circuit Tester

(65)

$13.35

Question:

I have a 2004 Jeep Liberty. The right and left turning lights work and the brake lights work on the trailer. The only problem is the tail lights on the trailer do not work when I turn on lights in the Jeep.what would cause that problem?

asked by: Dave B

Expert Reply:

It could be a couple of issues. The easiest one to rule out is that all of your fuses are working. You could have a blown fuse in your Jeep. I recommend looking at your Liberty's fuse box diagram and seeing if everything related to a towing function or your rear lights has a good fuse in it.

It could also be one of your connectors on the 4-way. You will want to use a circuit tester like item # PTW2993 to test the Jeep's connector to see if the problem is on it or the trailer. Assuming everything checks out there, then the issue is on the trailer side. If not and you have a problem on the Jeep, then you need to trace the wires coming from the connector looking for any damage. You should especially check the ground connection making sure it's clean and solid. It should be grounded to bare metal.

If the trailer is the problem, then start at its connector. Make sure the pins are clean and corrosion free. Then you will want to inspect the light wires throughout the trailer. Again check your grounds. They all need to be firmly attached to bare metal.

If all of this steps fail feel free to message me back directly but you'll most likely need to replace the wiring harness with the item # 118524 you were looking at.

expert reply by: Jerred H