There is nothing more frustrating than hooking up your trailer, bike carrier or caravan, only to find the lights are letting you down. Before you head out on the road, remember that you should never tow with faulty lights. It is not safe, for you or for other drivers.
If you are scratching your head over a lighting failure, we have put together a handy guide to help you figure out what might be going wrong. Here are some simple, safe checks you can do first, along with the most common causes.
Simple safe checks you can do first
Before you worry about complex electrical issues, run through these quick checks to rule out the basics:
- Try another vehicle: If you have access to another car with a working towbar, try plugging your trailer or bike carrier into it. This will quickly tell you if the fault lies with the trailer or your own car.
- Check the trailer board and cable: Look closely at the trailer lighting board, bulbs, and its own cable for any obvious signs of damage, cracks or wear.
- Inspect the car socket: Look inside your car’s socket with a torch. Check for water, green corrosion, or any bent pins.
- Check the plug connection: Make sure the plug is fully pushed into the socket and that the spring-loaded cover lid is not resting on the cable or stopping the plug from seating properly.
- Watch your dashboard: Pay attention to any dash warnings or bulb-failure messages that appear when you turn on your lights or indicators.
These simple steps often highlight the culprit right away without needing any tools.
Common causes of towbar electrics faults
If the quick checks do not reveal the problem, the issue usually falls into one of a few common categories:
- Corrosion and damaged sockets: Moisture gets inside over time, leading to green corrosion on the pins or a cracked socket housing.
- Worn trailer cables: Constant dragging and weather exposure can damage the wiring on older trailers or bike racks.
- Universal kit issues: If your car was fitted with a universal electrics kit instead of a car-specific setup, it can sometimes cause odd electrical faults on modern vehicles. Our universal electrics and dedicated electrics pages explain the difference.
- Coding and bulb-failure warnings: Many modern cars check their lighting circuits. If the towing electrics are not set up or coded properly, the car can show bulb-failure or towbar warnings that will not clear.
- Parking sensors not switching off: If your reversing sensors still beep when you reverse with a trailer or bike carrier attached, the electrics may not be telling the car that something is plugged in.
- Caravan not charging: If your leisure battery or fridge is not staying powered up while you drive, there is often an issue with the auxiliary charging feeds in a 13-pin setup. Our winter caravan checks post has more on this.
When to get help with your electrics
Sometimes a simple repair or a replacement socket is all it takes to get you back on the road. However, on newer cars, or where a universal kit has been wired in, a quick fix may not last. In those cases, installing fresh wiring or upgrading your setup is often the better, more reliable choice. We will always explain why and give you a clear quote before starting any work.
The Towbar Man repairs towbar electrics right at your home or workplace across the Midlands. You deal with Jake, our fitter with over 18 years of experience in the towing industry, from your very first email to the finished job. Whether you need help with trailer lights not working, dash warnings, parking sensor problems, or a 7 to 13-pin upgrade, we come directly to you. We cover towns across the Midlands, including Leicester, Nottingham, Derby, Loughborough and Coventry.
Find out more about our mobile service over on our towbar electrics repairs page.
Get a price
If you need help finding or fixing a towbar electrics fault, quotes are free with no obligation. For a new towbar and electrics, our instant price page gives an estimated fitted price from your reg and postcode. For a repair, message us on WhatsApp, or email sales@thetowbarman.com with your vehicle and what is going wrong. A photo of the socket helps. We aim to reply to all enquiries within 24 hours.