Can’t Get Running Lights To Work On Trailer

It can be frustrating when you’re all set to hit the road with your trailer, but then you realize that the running lights just won’t work. I’ve been there, and it’s definitely not a fun situation. However, with some troubleshooting and a bit of know-how, you can usually get to the bottom of the issue and have those lights shining brightly in no time.

Check the Wiring and Connections

The first step is to inspect the wiring and connections. Start by making sure the trailer is securely connected to the vehicle’s hitch. Then, take a look at the wiring harness and check for any visible damage or loose connections. It’s possible that the issue could be as simple as a loose wire or a corroded connection.

Test the Tow Vehicle

Once you’ve ruled out any obvious issues with the trailer’s wiring, it’s time to turn your attention to the tow vehicle. Check the vehicle’s owner’s manual to locate the fuse box and find the fuse for the trailer running lights. If the fuse is blown, replacing it may solve the problem. Additionally, use a circuit tester to check if the vehicle’s wiring harness is providing power to the trailer lights.

Inspect the Bulbs

If the wiring and connections seem to be in good condition and the tow vehicle is delivering power to the trailer, the next step is to inspect the bulbs themselves. In some cases, a simple bulb replacement may be all that’s needed to get the running lights working again. Make sure to use the correct type of bulb and that it’s securely seated in the socket.

Consider the Light Assembly

If all else fails, it’s worth considering whether the issue lies with the light assembly. Over time, the elements can take a toll on the lights, leading to corrosion or other damage. Inspect the light assembly for any signs of wear and tear, and if necessary, consider replacing the entire assembly.


Dealing with non-functioning running lights on a trailer can be a real headache, but with a methodical approach and some patience, it’s often possible to identify and resolve the issue. By checking the wiring and connections, testing the tow vehicle, inspecting the bulbs, and considering the light assembly, you can increase your chances of getting those lights back in working order. Remember, safety should always be the top priority when it comes to towing, so never hesitate to seek professional assistance if you’re uncertain about any aspect of the repair process. Happy and safe towing!