Your Guide To Towbar Electrics

Your Guide To Towbar Electrics

Choosing the correct towbar wiring kit is essential to making sure you are safe on the road. You need towbar electrics for trailers, caravans or bike racks because the lights on your vehicle will be hidden. So, an electrics kit keeps car lights and signals visible to other road users.

  • Towbar Electrics: Socket Types
  • Towbar Electrics: Wiring Kits
  • Towbar Electrics Adapters
  • How To Test Towbar Electrics
  • Towbar Electrics FAQs

Towbar Electrics: Socket Types

There are two types of towbar sockets: 7 pin and 13 pin. The one you need may depend on your vehicle, trailer, caravan or bike rack, as each will have different electrical requirements. If your car and trailer have different plugs and sockets, you'll need an adapter to convert the towing electrical connections so they 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 basic brake, indicator and tail light functions on your bike rack, trailer or caravan for simple towing. If you have a towbar-mounted bike rack which covers the lights on your vehicle, you'll need a lighting board so light signals are still visible.

Our 7 pin towbar wiring diagram will help you visualise how the functions connect with towbar wiring colours.

graphic showing a 7 pin electric socket

13 Pin Socket

13 pin electrics combines both the basic and advanced electrical features needed for towing within one plug. Each pin in the 13 pin towing socket has a specific function with a corresponding colour. This allows you to see which wire in the plug provides which electrical function. If you are towing a trailer or caravan, it connects to your vehicle's advanced features including trailer stability control and provides power inside your caravan for appliances.

See our 13 pin electrics diagram below to see which pins supply which electrical functions.

diagram of a 13 pin electric socket

Towbar Electrics: Wiring Kits

There are two types of towbar wiring kits available but 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 whereas installing a universal wiring kit could impact your warranty.

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

What is a dedicated towbar wiring kit?

Dedicated towbar wiring kits have been designed to sync with your vehicle's electrical system. A dedicated towbar wiring kit is the best choice as it is the only wiring that will synchronise with your 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 car's warning system.

What is a universal wiring kit?

Universal wiring kits are compatible with most older 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, with limited functionality.

Universal wiring kits are not suitable for most modern cars with sophisticated electrical systems as they can not support vehicle-specific functions. You will also need a towbar wiring bypass relay for modern vehicles 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. A universal wiring kit could make lights too dim, cut the power supply or cause the fuse to blow in your vehicle so a bypass relay isolates the power supply.

A bypass relay sends electrical pulses when a function is activated so power is only supplied when it is needed. This takes the strain off your car battery and also protects 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 are different to older vehicles. To see how a bypass relay fits into your towbar electrics, please see our towbar bypass relay wiring diagram below.

graphic of a bypass relay diagram

Towbar Electrics Adapters

There are four potential types of towbar electrics adapters that you might need. This is usually necessary when your towbar electrics and trailer, caravan or bike rack electrics don't match up. For example, If your towbar has 13 pin electrics and your trailer has 7 pin electrics, you will need an adapter to make the two kits compatible. With this in mind, the four main types of vehicle plug adapters include:

  • 7 pin to 13 pin adapter
  • 13 pin to 7 pin adapter
  • 13 pin to 2x 7 pin (twin) adapter
  • 2x 7 pin (twin) to 13 pin adapter

7 pin to 13 pin adapter

A 7 pin to 13 pin adapter is necessary if your towbar has 7 pin electrics but your bike rack, trailer or caravan has 13 pin electrics. It is important to note, however, that if your towbar only has 7 pin electrics, then it will only be able to provide 7 pin electrics even when using an adapter. This means that even if you are towing a caravan, only the basic lighting functions will be powered, not the fridge or any of the functions inside the caravan.

13 pin to 7 pin adapter

On the other hand, a 13 pin to 7 pin adapter will be needed if your vehicle has 13 pin electrics but the trailer, caravan or bike rack has 7 pin electrics. Even if your vehicle has been fitted with 13 pin electrics for advanced features, these will not be utilised with a 13 to 7 pin adapter. That's because whatever you are towing does not have a sophisticated electrical system so it will only power the basic 7 pin electrics like rear lights.

13 pin to 2x 7 pin (twin) adapter

It sounds a bit more complicated when we start talking about twin adapters but it's really not that different. A 13 pin to twin adapter would be necessary if your towbar has been fitted with 13 pin electrics but whatever you're towing has two 7 pin sockets. These adapters are typically used for newer vehicles with 13 pin electrics that tow oldr caravans with twin electrics.

2x 7 pin (twin) to 13 pin adapter

In contrast, a vehicle fitted with 2x 7 pin electrics towing a bike rack, caravan or trailer with 13 pin electrics will require a twin to 13 pin adapter. Using an adapter means you don't need to replace the towbar and electrics and the 13 pin functions on whatever you are towing, like lights and interior electrics, will still function while you're towing.

If your wiring kits don't match up, it is essential that you use the right vehicle plug adapter so your vehicle lights are still visible to other road users.

Learn more about finding the right vehicle plug adapter here.

How To Test Towbar Electrics

When you hitch up a trailer, caravan or bike rack, it's vital that you test your towbar electrics are working properly before you pull off. This is so other road users will be able to see and respond to your light signals appropriately while on the road. So, what is the best way to test your lights and ensure everything is working correctly?

Use a dedicated 13 pin socket tester

When your towbar electrics have been installed, or when your car goes in for an MOT, your towbar electrics should be checked with a dedicated socket tester. If you have access to a socket tester, you can also check your towbar electrics are in working order at home, before you start towing.

  1. Lift the towing socket, line up the tester plug, insert it and lock it into place
  2. The 12V CONTINUOUS LED should light up straight away if the socket is wired for continuous 12V supply
  3. Sit in your car with the socket tester and press the 'Test' button to make sure the unit is working anf the LEDs light up
  4. Turn on the ignition without turning on the engine. The 12V IGNITION LED should light up
  5. You should now check the following light functions are working:
  • Right and left indicators
  • Side lights
  • Brake lights
  • Fog lights
  • Reverse lights
  1. When carrying out each of your checks, the relevant LED lights should illuminate on the socket tester
  2. When all checks are complete, remove the tester plug and replace the towing socket cover

Ask someone to help

Possibly the easiest, and cheapest, way to check that your towbar electrics are working correctly is to hitch up your trailer, caravan or bike rack and have someone check if the lights are all working.

  1. Sit in the driver's seat of the car, turn the ignition on and leave the handbrake on
  2. Ask a trusted friend or family member to stand behind your trailer, caravan or bike rack while you test the lights
  3. In turn, while the handbrake remains on, test each of your light signals to make sure they are working including:
  • Right and left indicators
  • Side lights
  • Brake lights
  • Fog lights
  • Reverse lights
  1. Once you have tested all of the lights are working correctly, it is now safe to tow

It is essential to test your towbar electrics before towing so you can be sure all of your light signals are working properly before you set off. That way, you are keeping yourself and other road users safe while you are towing.

Towbar Electrics FAQs

Understanding towing electrics can be tricky. That's why we've answered your frequent questions about towing electrics to help make choosing an electrics kit easier for you.

Which towbar electrics are best for me?

The best towbar wiring kit for your car depends on the age, make and model along with what you are towing and what sockets are fitted to your vehicle and trailer. However, if you have a newer vehicle, a dedicated electrics kit will be the best choice.

Do I need a towbar electrics adapter?

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

What towbar electrics do I need?

The best way to find your perfect towbar wiring 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 select your towbar.

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 is a legal requirement when towing.

Search for towbar wiring kits by entering your car details here.

What is a vehicle-specific wiring kit?

A vehicle-specific wiring kit is designed to sync perfectly with your vehicle electrics. It will be specific to the make, model and year of your vehicle so it can work alongside any advanced features your vehicle may have while you are towing. Unlike a universal wiring kit, vehicle-specific wiring kits can only be used with the vehicle they were designed for.

With a vehicle-specific wiring kit, you will be able to activate any advanced features your vehicle may have to make towing even safer. This might include things like trailer stability control, but it may be necessary to update your vehicle's software to use these features.

Find a vehicle-specific wiring kit now.

What is the difference between single and twin electrics?

Single electrics use one plug to connect your vehicle and trailer electrics. 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 for brake, indicator and fog lights. 12S electrics provide the 'supplementary', or advanced, electricals through an additional 7 pin twin electrics plug. This includes reverse lights, interior lights and powering the fridge in a caravan. A 13 pin electrical plug combines both the 12N and 12S electrics in one plug and is common on newer cars, trailers or caravans.

How much does it cost to fit a towbar and electrics?

The cost of fitting a new towbar and vehicle electrics can vary massively as it depends on multiple factors. This includes:

  • The make, model and age of your vehicle
  • The towbar you choose
  • The wiring kit you choose
  • Towbar fitting

Your vehicle

Different towbars have been designed to suit different vehicles, with newer vehicles benefiting from the latest in towbar technology. As a result, you may find that towbars designed for older vehicles are cheaper than those designed for newer vehicles as they were perhaps not designed with the latest towbar technology in mind.

The towbar

Just like the car you have affects the price of your towbar fitting, so does the towbar you choose. There are four main types of towbar which vary in price from cheapest, to most expensive:

  • Fixed Flange Towbar (Least expensive)
  • Fixed Swan Neck Towbar
  • Detachable Swan Towbar
  • Detachable Flange Towbar (Most expensive)

With this in mind, if you choose a fixed flange towbar, it is likely to be considerably cheaper than a detachable flange towbar.

Towbar electrics

The towbar wiring kit you choose also impacts how much it will cost. A universal electrics kit is usually cheaper than a vehicle-specific kit because it only accommodates the basic electrical towing functions on your vehicle like the light signals. A vehicle-specific kit however synchronises perfectly with your vehicle's electrical system and enables you to utilise advanced features like trailer stability control.

Towbar fitting

While it is possible to fit a towbar yourself, we certainly wouldn't recommend it unless you are a trained mechanic. When you book towbar fitting through Witter, you can choose fitting at an approved garage or mobile fitting, at a time and place to suit you, for an additional £35. You can also select an optional vehicle system upgrade for £72.

When considering the overall cost of a towbar with an electrics kit, a fixed flange towbar with a universal electrics kit is significantly cheaper than a detachable flange towbar with a vehicle-specific electrics kit. So, considering all of these factors, you can expect to pay anywhere from £300 to £1,000 for the towbar, electrics kit and fitting.

There are lots of factors to consider when choosing the right towbar electrics, and lots that you need to learn to make sure you choose the right kit for your car. But with the right research and knowledge, you can be sure to choose the right towbar wiring kit, as well as feeling confident in testing and using it correctly.

Find your dedicated electrics kit now.

Learn more by reading our additional towbar FAQs here.