Towbar Wiring

There are two ways of connecting the tow bar wiring to your car. To help you decide which is right for you and your vehicle we have outlined these below.

Universal Bypass

Universal Bypass wiring is a simple way of connecting your tow bar wiring to your car whilst protecting the cars electrical systems. This system “bypasses” the cars complex electrical systems and only connects to the vehicles lighting functions allowing the trailer lights to work.

If you require your cars many safety features to work then this is not the system for you as the tow bar wiring is isolated from the vehicles wiring and the car will not know it is towing.

However, if you have an older car without these features or do not require any of the safety features to work then the bypass system when properly installed can be a simple cost-effective solution.

  • Cost-Effective
  • Universal Fitting
  • Fog light cut out
  • Trailer stability programs
  • Parking aids disabled

Dedicated Vehicle Specific Wiring

Dedicated vehicle specific kits are designed to fit to the cars electrical systems as the manufacturer intended, incorporating many safety features that modern cars have today. Such as trailer stability control or electronic stability program.

Many dedicated kits have to be coded or programmed to allow these functions to operate, at Top Fit Tow Bars we have invested in the equipment to code your vehicle at the time of install.

With car electronics getting ever more complex it is important that you choose the best way for your tow bar and wiring installation. Most of the wiring kits that we use are manufacturers original equipment so if your car is still within warranty then this is the best option for you.

  • Vehicle specific
  • Warranty protected
  • Parking aids disabled
  • Trailer stability programs
  • Higher cost
  • More complex to fit

7 Pin (12N)

This is the most common and cost-effective type of connector that has been used in the UK for many years. It will fulfill all normal rowing requirements and can be used with lighting boards, cycle carriers, caravans, garden trailers, plant trailers and horse boxes. In fact, almost anything you can connect to a towbar that requires road lights.


7 Pin (12S)

The 12S connector has been used in the UK for many years. It provides a permanent and switched power supply and reverse light function. The permanent supply provides power to the interior lights when the engine is turned off and is switched to charge the caravan battery when the engine is running. The switched power supply provides power to the caravan fridge when the engine is running. A 12S socket can also be used for horse boxes with internal batteries and tipper trailers with electric lifts. It can be distinguished by a grey flip cover in most cases.

ISO 13 Pin

This is a single connector of similar size to that of a 7 pin connector but it contains both 12N and 12S functions in one. It is a sealed connection with a unique twist lock system that is secure, neat and reliable. All caravans manufactured for the 2009 season onwards will have an ISO 13 pin connector as standard. The trailer industry will move towards fitting 13 pin plugs and by 2012 we expect this to be the industry standard.