Troubleshooting Running Lights Not Working on Trailer

Updated 08/04/2017 | Published 08/03/2017

Question:

I have an older boat trailer from the 90s and recently just put a new harness on the entire trailer. The brakes and signals work on the trailer aa well as my tester, but the running lights do not. There are no breaks in the wires that are visible. I am thinking it may be a fuse because the problem is on the van ford freestar. My friends truck has the same harness female end so we plugged it in and it worked on his. Is there anyway you can help me with this issue.

asked by: Davis M

Expert Reply:

Since all of the trailer lights worked perfectly with your friend's vehicle, the issue certainly seems to be on the vehicle side for your Ford Freestar.

I recommend starting by testing the vehicle side trailer connector on your Freestar. You can use a circuit tester like # PTW2993 to test the pins on the connector. If you are not receiving any power at the running light circuit, this will further indicate that the issue is somewhere along the vehicle side wiring. You can also check to make sure that the connector itself is free of any dirt or corrosion that might be preventing a secure connection with the trailer connector.

You will then want to trace the wiring up from the connector on the vehicle and look for any signs of shorting such as cut or exposed wires, simply fixing as needed.

If you are unable to locate and resolve the issue, please let me know and I will be happy to look into this further. I have also attached a wiring troubleshooting article that you might find helpful.

expert reply by: Chris R