Troubleshooting All Trailer Lights Stopped Working with Dodge ProMaster 3500  

Question:

Expert Reply:

If all of the trailer lights stopped working, I first recommend testing the connector on your Dodge ProMaster. You can use a circuit tester like # PTW2993 to test the pins while you have a buddy run through the lighting functions in the vehicle. This will help you to at least focus on the vehicle or the trailer as the source for the issue. If you don't receive power at the connector with the lighting functions activated, then you know the issue is with the ProMaster. If you do get appropriate power at the connector, then the problem is actually on the trailer side.

Starting with the vehicle, you can certainly check to make sure all of the towing related fuses and relays are present and in good condition. You can take a look at your owner's manual for the ProMaster to see if it lists any fuse or relay locations that are for trailer lights. I was not able to find the location for any relays when looking at the online version of the manual.

Otherwise, make sure all the connections for the wiring harness on the vehicle are secure and connected correctly. You can check the connector itself for any debris or corrosion that might be built up behind the pins, cleaning out as needed. Test the wires with the circuit tester before they reach the connector to see if they get power there, which would indicate that the connector is bad and should be replaced.

If you find that the issue is on the trailer, you will first want to make sure the trailer connector is free of debris or corrosion. Also check to make sure that the main connector grounds are attached to clean, corrosion free bare metal surfaces. Take a look at the ground connections for the light assembles themselves, whether they ground through a dedicated wire or through their mounting hardware.

If you are still having issues, please let me know and we can continue to troubleshoot.

expert reply by: Chris R

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