Towbar Electrics: The Definitive Guide

Choosing the correct towbar electrics kit is essential to making sure you are safe on the road. When you are towing a trailer, caravan or bike rack, the lights on your vehicle will be hidden so it is it is important to have a towbar electrics kit so your car lights and signals are visible to other road users.

Towbar Electrics

What is a towbar wiring kit?

A towbar wiring kit connects the electrics and lights on your car to the lighting board on your trailer, caravan or bike rack. This means that when you indicate or brake, these lights will be illuminated on your trailer or caravan as well, which is a legal requirement when towing.

What is the difference between single and twin electrics?

There are 3 types of towbar electrics plugs, including single 7 pin electrics, single 13 pin electrics and twin electrics. Single electrics use one plug to connect your vehicle and trailer electrics, whereas twin electrics require two 7 pin plugs, which is usually necessary for towing older caravans or trailers.

What are 12N and 12S?

12N electrics provide the ‘normal’ legal lighting requirements, via a single 7 pin electrics plug. These include the brake, indicator and fog lights. 12S electrics provide the ‘supplementary’, or advanced, electricals through an additional 7 pin twin electrics plug. The supplementary electrics include reverse lights, interior lights and power the fridge in a caravan. A 13 pin electrical plug combines both the 12N and 12S electrics in one plug and is more common on newer cars, trailers or caravans.

Towbar Socket Types

There are two types of towbar sockets. The one you need may depend on your vehicle, trailer, caravan or bike rack, as each will have different electrical requirements. Additionally, if your car and trailer have different towing sockets, you can purchase an adapter to convert the towbar electrical plugs to work in sync.

7 Pin Towbar Wiring

7 pin electrics provide the normal or legal lighting requirements for towing. A 7 pin towbar plug will provide brake, indicate and tail light functions on your bike rack, trailer or caravan and is suitable for simple towing.

If you have a towbar mounted bike rack which covers your vehicle lights, you will need a lighting board on your bike rack so your light signals are still visible. Additionally, if you only need basic light functions on a small trailer, 7 pin towbar wiring will support these needs as you are unlikely to require functions such as trailer stability control when carrying bikes on your towbar.

To help you understand how 7 pin towbar wiring works, our helpful diagram will help you visualise how the functions connect with towbar wiring colours.

13 Pin Towing Socket

13 pin electrics combines both the basic and advanced electrical features needed for towing within one plug. This makes a 13 pin plug tidier and easier to use as all of the functions are encased within a single plug. Each pin in the 13 pin towing socket has a specific function with a corresponding colour which allows you to see which wire in the plug provides which electrical function.

If you are towing a trailer or caravan, you will benefit from a 13 pin towing socket as this will connect to your vehicle’s advanced features. This includes trailer stability control and providing power inside your caravan for appliances such as the fridge, which would be essential if you need to keep food fresh while travelling.

See how a 13 pin towing socket works in our helpful colour coded diagram, showing you which pins supply which electrical functions.

Towbar Wiring Kits

There are two types of towbar wiring kit available and the one you need will usually depend on the age of your vehicle. It is always best to buy a vehicle specific wiring kit as this will synchronise perfectly with your car’s electrical system and installing a universal wiring kit could impact on your warranty.

Find the best towbar wiring kit for you by entering your vehicle registration number below.

What is a dedicated towbar wiring kit?

Dedicated towbar wiring kits have been designed to sync with your vehicle’s electrical system. Modern vehicles have complex technical systems so vehicle specific towbar wiring kits have been developed to support these complex functions.

A dedicated towbar wiring kit it the best choice for your towbar electrics as it the only wiring that will synchronise with advanced vehicle functions. These could include enabling trailer stability control or the reverse lights on the back of your trailer.

By installing a vehicle specific towbar wiring kit, you will not invalidate your vehicle warranty as this is the only option which works with manufacturer requirements. Dedicated wiring kits can also alert you of a trailer lighting failure as it integrates with your cars warning system.

What is a universal wiring kit?

Universal wiring kits are compatible with most vehicles and support the basic electrical functions needed for towing. If you have a tight budget and schedule, a universal wiring kit is cheap, quick to install and can provide you with all of the basic components needed for towing.

However, as a universal wiring kit only provides the basic requirements, functionality is limited. Universal wiring kits are not suitable for most modern cars with sophisticated electrical systems as they can not support vehicle specific functions. Additionally, if your vehicle is still under warranty, installing a universal towbar wiring kit could affect your warranty as it does not meet specific manufacturer requirements. You will also need to install a towbar wiring bypass relay if you have a modern vehicle with a complex electrical system.

What is a towbar wiring bypass relay?

A towbar wiring bypass relay can be fitted between the towbar wiring and vehicle wiring to prevent too much power from being taken directly from the vehicle battery. In most modern vehicles, one connection point could operate various systems and a universal wiring kit is not sophisticated enough to accommodate complex electrical systems. A universal wiring kit could make the lights too dim, cut the power supply or cause the fuse to blow in your vehicle, so you would need to install a towbar wiring bypass relay to isolate the power supply.

Rather than supplying a constant power source from the vehicle battery to the trailer or caravan, a bypass relay sends electrical pulses when a function is activated. For example, rather than sending a constant power supply to the brake lights, power will only be activated through the relay when you press the brake pedal and deactivated when you take your foot off the pedal. This way, power is supplied when it is needed, taking the strain off your car battery and also protecting it from potential faults that could occur from trailer wiring.

A bypass relay is necessary if you are fitting a universal wiring system in a modern car, as they work differently from older vehicles. To protect your vehicle’s electrical system from damage, we would always recommend having vehicle specific towbar electrics fitted by a professional.

To see how a bypass relay fits into your towbar electrics, please see our towbar bypass relay wiring diagram below.

Which towbar electrics are best for me?

The best towbar wiring kit for your car will depend on the age, make and model of your car. It will also depend upon what you are towing and which sockets are fitted to your vehicle and trailer.

Do I need a towbar electrics adapter?

If your towbar has a 7 pin electrics plug but your caravan has a 13 pin plug, then you will need a 7 pin to 13 pin adapter. This will only extend the 7 pin functions - it won’t provide the additional functions you would have with a 13 pin plug.

If your car has a 13 pin electrics plug but your caravan or trailer has a 7 pin electrics plug, then you will need a 13 pin to 7 pin adapter. This would be suitable for towing a bike rack or standard trailer or you would need a 13 pin to twin socket adapter to tow an older caravan with twin electrics.

No matter what size electric plugs you have on your towbar, caravan, bike rack or trailer, a towbar electrics adapter will enable you to safely connect your car and whatever you are towing without the need to change the electrical plugs.

What towbar electrics do I need?

The best way to find your perfect towbar electrics kit is to enter your vehicle registration or the make, model and age of your vehicle so we can find the best towbar wiring kit when you selec your towbar.