How to Locate & Diagnose Trailer Wiring Problems

Wiring problems are notoriously difficult to deal with as wiring can often be hidden, making t difficult to visually spot any issue. However, developing an understanding of trailer electrics and the most common issues will help you to diagnose the issue, locate the fault, and fix it. But if DIY fixing is not possible due to severe and complicated wiring issues, the best option is to ask for help from a trusted car auto electrician.

That could be essential when you need to use your trailer, whatever the reason. Of course, it helps to be in contact with a good automotive electrician. They will be able to fix any issues you can’t resolve and even service the wiring regularly.

Lights Aren’t Working

Your trailer should have several lights on the rear of it. These will be the standard running lights, indicators, and brake lights. If you notice that all of these lights have stopped working then the most likely culprit is a fuse in the wiring system.

You’ll want to check if you have a fuse just for the trailer in your car fuse box. If the lights are also out on your car then the fuse in the car fusebox will be the culprit. But, if it’s just the trailer you’ll need to trace the trailing wiring to find the inline fuse and replace it. Don’t forget to check that the power to the trailer is connected.

If this isn’t the issue you may have a damaged power wire to the trailer. However, as the power is directed to each of the lights from the associated vehicle circuits, you would need to have damaged several wires for all the electrics to have stopped working.

Of course, the issue could be related to a corroded plug or, if it has been pulled hard, the wiring inside could be damaged.

Fading Lights

Should you find that the lights are working but they are fading quickly or that one indicator flashing is causing a brake or running light to flash, then you probably have an earth issue. The chassis wiring should be grounded into the vehicle system.

You’ll want to locate the trailer ground wire and make sure it has a good connection. Bad grounding causes lights to fade and can even prevent them from working altogether.

Flickering Lights

If your trailer lights are constantly flickering then this can be a sign of an earthing issue. But, it may also means that the trailer wiring is short circuiting. In this instance, the wiring is likely to be damaged and two cables are connecting to each other, temporarily shorting the circuits.

Because the trailer is constantly moving while being towed the short doesn’t cause a permanent cut out, instead of making the lights flicker.

Final Thoughts

The majority of trailer wiring issues are related to loose connections and damaged wires. Simply inspecting your trailer regularly will help you identify any issue and resolve it before it becomes a problem on the road.

Don’t forget, that wiring issues can cause your indicators not to work, meaning that other road users won’t know what you are doing and are likely to crash into you. That’s not the outcome you want.