Running Lights Not Working on Trailer  

Question:

Expert Reply:

For starters, you will want to turn the vehicle on and test the running light circuit (brown wire) on the vehicle's 4-way with a circuit tester like part # PTW2993. If power is present, then you know the problem in on the trailer. If power is not present, then you know the problem is on the vehicle.

If the error is on the vehicle side, then you will first want to start by checking the fuse box to see if any fuses associated with the trailer or running lights are blown. If not, you can proceed by checking the running light circuit just before and after the converter box. If power is entering the converter box but not coming out, then the converter box is bad and will need to be replaced. If power is not entering the converter box, then you will need to trace the running light wire back to its source and check for broken or loose connections.

If the error is on the trailer side then you will first want to start by making sure the lights are properly grounded whether that be through the mounting hardware or a ground wire. You will also want to make sure the trailer connector is grounded properly. I would then proceed by checking the running light wire from each light and tracing it back to the trailer connector while checking or breaks or loose connections.

Another possible cause of the running lights not working is corrosion on the trailer connector pins. You can clean these pins with some electrical contact cleaner and then use some dielectric grease like part # 11755 before mating the connectors back together. If this does not fix your problem please let me know and I would be happy to provide additional troubleshooting steps for you.

expert reply by: Conner L

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