Troubleshooting No Running Lights on Trailer

Updated 05/01/2018 | Published 04/29/2018

Question:

Why no running lights bit all others work

asked by: Angie

Expert Reply:

The first thing I recommend doing is using a circuit tester like # PTW2993 to test the pins at the vehicle side connector. This will help isolate the problem to either the vehicle side or the trailer side. Test the running light pin at the connector while the function is activated on the vehicle. If you do receive a signal there, you know the issue is somewhere on the trailer side. If you don't get any signal, you can focus your attention on the vehicle.

If you didn't get any signal at the vehicle side connector, you will want to make sure the connector itself is free of any debris or corrosion, cleaning out as needed. Then make sure all the wiring connections are secure and check for any missing or damaged fuses. You can take a look at the vehicle's owners manual for any fuse locations related to trailer lights.

Then, if you find the issue is on the trailer side, first check the trailer connector for debris or corrosion. Check to make sure the grounds are securely connected to a clean, bare metal surface. If the ground connections are sound, you will want to check the wiring itself for any places where the wiring is corroded or exposed, replacing when needed.

If you are still unable to locate the issue, please let me know and we can continue to troubleshoot. I have also attached a trailer wiring article that you might find helpful.

expert reply by: Chris R