Diagnosing Ground Problem on Trailer Towed by 2008 Jeep Liberty

Question:

I have a 2008 Jeep Liberty.I would like to know what is wrong with my trailer lights My tail lights to my trailer do not work when my headlights are on.

asked by: James S

Expert Reply:

You are describing one of the classic symptoms of an insufficient ground connection. When you turn on the vehicle headlights and the running lights on the trailer come on, the system is pulling maximum amperage. If there is poor ground connection, this is when it will show itself.

Make sure that the ground wire for the trailer connector on your Liberty is securely attached to clean metal on the vehicle chassis or frame. Check the connector on the trailer. The white wire from the trailer connector should be securely fastened to the trailer frame, usually on the tongue. Make sure the connection point is not corroded. Most trailer lamps get their ground connection by being in direct contact with the trailer frame. Make sure each lamp is securely connected to the trailer frame, and that the points where they contact each other (like mounting studs fastened to the trailer frame) are not corroded. If the lamps are not connected to the trailer frame, but to plastic or wood, make sure a ground wire is ran from the lamp to the frame.

The last possibility to explore is in the trailer design. If the trailer has a tilting bed, it is possible the ground is not passing through the pivot point resulting in a poor ground. The solution to this is to run a ground wire from the trailer frame to the tilting portion of the trailer. This will maintain a continuous ground connection on the trailer.

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expert reply by: Mike L

Mike T.

5/3/2020

Do you have a version of this that connects to the big round plug on the back of my 2008 Jeep liberty sport with tow package?

Chris R.

5/6/2020

Are you looking for a 4-Way harness to install on your Jeep Liberty? If so, we do have the Tekonsha # 118381, that's designed specifically for the 2008 Jeep Liberty that came equipped with the factory 7-Way connector (which I believe is what you meant by the big round plug on the back). This will plug right into a factory port behind the bumper. If I'm misunderstanding your question please just let me know.