Car TipsNot Working

Trailer Running Lights Not Working [Complete Guide]

Trailer running lights are an essential safety feature, as they help other drivers to see your trailer in low-light conditions. However, if you’re experiencing issues with your trailer running lights not working, it can be frustrating and potentially dangerous. In this article, we’ll explore some of the common causes and what you can do to fix them.

4 Ways to Fix Trailer Running Lights Not Working:

Check the Wiring Connections

The first thing you should do is check the wiring connections on your trailer. A loose or corroded connection could be the cause of the problem. Check to make sure that all the connections are secure and free of corrosion. If you notice any corrosion, clean it off with a wire brush.

Check the Fuses

If the wiring connections are all secure, the next step is to check the fuses. Most trailers have a fuse box located under the hood of the tow vehicle. Check the owner’s manual for your tow vehicle to locate the fuse box. Once you find the fuse box, check to see if any of the fuses are blown. If you find a blown fuse, replace it with a new one.

Test the Bulbs

If the wiring connections and fuses are both in good condition, it’s time to test the bulbs. Start by removing the light cover and pulling out the bulb. Check to see if the filament is broken. If it is, replace the bulb with a new one. If the bulb is in good condition, you’ll need to test the socket with a multimeter. Set the multimeter to the ohms setting and touch the probes to the metal contacts in the socket. If the multimeter reads zero ohms, the socket is working properly. If it doesn’t read zero ohms, you’ll need to replace the socket.

Check the Ground Connection

If none of the above solutions work, it’s possible that the ground connection is faulty. Check the ground wire to make sure it’s securely attached to the trailer frame. If the ground wire is loose or corroded, clean it off with a wire brush and reattach it securely.

What would cause my trailer running lights not to work?

Several factors can cause trailer running lights not to work. Loose or corroded wiring connections are a common issue that can interrupt the flow of electricity to the lights. Blown fuses in the tow vehicle’s fuse box can also cut off the power supply to the lights. Damaged or broken bulbs can result in non-functional lights as well.

Another possible cause of non-functional trailer running lights is a faulty ground connection, where the ground wire may have come loose or corroded. If you experience any problems with your trailer running lights, it’s essential to investigate and resolve the issue promptly to maintain the safety of yourself and other drivers on the road.

Why do all my Trailer Lights work except the Running Lights?

If all your trailer lights work except the running lights, there are a few possible reasons why this could be happening. The running lights are typically wired separately from the brake lights, turn signals, and other lights on the trailer. So, it’s possible that the wiring for the running lights is damaged or disconnected, causing them not to work.

Another possible cause could be a blown fuse that affects the running lights only. Additionally, the bulbs for the running lights could be burned out or damaged. It’s important to check these potential issues, resolve them promptly, and ensure that all trailer lights are functioning correctly to maintain road safety.

What Fuse is for the trailer running lights?

The specific fuse that is for the trailer running lights can vary depending on the make and model of the tow vehicle. Typically, the trailer running lights are connected to a fuse in the tow vehicle’s fuse box, which is often located under the hood.

To find the fuse that is responsible for the trailer running lights, consult the owner’s manual for your vehicle or look for a fuse labeled “TRLR” or “Trailer” in the fuse box. If you’re having trouble locating the correct fuse, you can use a test light or a multimeter to check the fuses until you find the one that is blown or not functioning correctly. It’s important to replace any blown fuses with the correct amperage rating to prevent any electrical issues or hazards while on the road.


In conclusion, troubleshooting trailer running lights that are not working requires a systematic approach. Start by checking the wiring connections, fuses, bulbs, and ground connections. By following this guide, you should be able to fix the issue and get back on the road safely. Remember, if you’re not comfortable working with electrical systems, it’s always best to seek the assistance of a professional mechanic.

Related Posts

Rachael McAdams

I'm Rachael, CEO of AutoGeeX, bring unrivaled expertise and passion to the automotive industry. With extensive knowledge and a deep understanding of cars, she shares captivating tales, invaluable insights, and practical tips with readers. As an active presence in the car community, Rachael ignites excitement, revolutionizing the automotive landscape with AutoGeeX's pursuit of perfection.

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button