Running Lights Will Not Work on Trailer Towed with a 2012 Dodge Journey

Question:

I have a two wire system on the trailer, I think. There are two filiments in the bulb. The turn signal and brake lights work but not the running lights. What an I doing wrong? 2012 Doge Journey

asked by: Paul M

Expert Reply:

Almost all trailers do use 2 wire system. The 2-wire system means there is one wire for the running lights on each side of the trailer and one wire for the turn signal and brake light. It is likely that both of these wires are running to the dual filament bulbs. The brake light and turn signal will use the brighter or higher intensity filament and the running lights will use the dimmer or lower intensity filament.

To troubleshoot your issue, I recommend starting at the trailer connectors. Use a circuit tester, like part # PTW2993, to test the pins of the 4-way trailer connector on your tow vehicle. The pin closest to the exposed ground pin should be hot when you turn on the head lights. I have attached a video my coworker made showing how to test a 4-flat trailer connector for you to check out.

If you do have power for the running lights on the 4-way trailer connector, then it sounds like you may have a short on the running light circuit somewhere on the trailer. I recommend starting at the connector on the trailer and work your way back toward the taillights. Look for any corrosion build up or damaged wiring that could be causing a short. It would also be a good idea to make sure the trailer connector and taillights have good ground connections.

If there is no power for the running lights at the vehicle side connector, then we know the issue is on the vehicle side. After looking at your previous orders, it looks like you may have installed a Universal Circuit Protected Modulite wiring harness on your 2012 Dodge Journey. I recommend using the circuit tester to test the wires going into the converter box. If you have power for the running lights going into the converter box, but not coming out, then the converter box is bad, and the wiring harness would need to be replaced. If you do not have power going into the converter box, then check the wire connection for the running lights.

If you are unable to come up with a solution or find the problem after following these steps, let me know what you come up with and we can do further troubleshooting. I have attached an FAQ article on trailer wiring that should help when you are troubleshooting the wiring on your trailer.

expert reply by: John H