Troubleshooting Lights that Do Not Work on 2007 Jeep Grand Cherokee with Trailer Connected  

Question:

Expert Reply:

The first thing I would do is check out the trailer wiring and make sure that everything is wired properly and there are no shorted, broken, pinched or frayed wires and that all of the ground connections on the trailer are securely attached. Be sure to check the ground condition where the lights are attached to the brackets and where the brackets are attached to the trailer frame. If you need a circuit tester, you could use something like # PTW2993.

If the trailer functions properly then there may be too many lights on the trailer for your Jeep Grand Cherokee wiring system. If there are more than two taillights and two marker lights on the sides of the trailer it is possible that you will need to install a circuit protected Modulite powered converter, item # 118425, so that the trailer lights are powered by the vehicles battery instead of the electrical system.

Finally the trouble may be the wiring harness itself. If the jeep lighting is not working properly with the harness installed and no trailer connected, I would remove the harness from the vehicle and plug the OEM connectors back in to see if the vehicles lighting returns to normal. If the vehicles lights only malfunction when the trailer is connected check to be sure the connection points are securely locked together and that the 4-Way is working properly without the trailer connected. If the connector functions properly without a trailer connected the above remedies should solve the problem.

expert reply by: Robert G

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