Towbar Electrics Explained

Socket Types Explained

You need to decide which type of socket will suit your towing needs!
There are 3 types of sockets currently being used and below we have outlined their functionality.
Additional relays are or maybe required when wiring up certain model vehicles, alternatively vehicle specific wiring kits can also be supplied. Details on relays and vehicle specific wiring looms can be found in the wiring section of our web site.

7 Pin – 12N Socket

This is a plain black socket containing 7 Pins and is the more commonly used system today, although on newer caravans, trailers & bike carriers etc. a more sophisticated 13 Pin system is being introduced. See further details below.
The functions of this standard 7 Pin socket are to operate brakes, sides and indicators.
Some caravans now have built in Stabilization systems such as Al-Ko's 'ATC' which help to prevent 'snaking' when towing. This system along with the reverse light would only function from a Double Electrics (12'N' & 12'S') or 13-pin systems


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7 Pin – 12S Socket

(Also referred to as twin electrics when fitted in conjunction with the 12N socket)
This is a grey or white socket has a different pin configuration to the 7 Pin 12N black socket.
The 12S socket provides power to operate the interior functions of the caravan such as the interior lights, run the fridge and charge the battery whilst you are towing.
The dual 12N and 12S system has been replaced with the 13 Pin system on caravans since approximately 2008. Please see details below on 13 Pin.
Even though your caravan maybe fitted with dual plugs, not everybody will avail of its functionality and it may not be necessary to have your tow vehicle fitted with the 12S socket.


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13 Pin – Socket

This new system has been standard throughout Europe for several years and most new vehicles purchased with factory fitted towbars will come with this 13 Pin system.
This system is replacing the 2 separate sockets (12N & 12S), for which the 13 pin socket is essentially the two 7 pin sockets merged into one, providing the standard functions of the 12N system being, sidelights, brakes, indicators and fog, but can also include the additional functions of the 12S being, reverse lights, permanent live and switched 12v supply.
The 13 Pin Socket may also be fitted without the 12S function if reverse lights, permanent live and switched 12v supply are not required, mainly used for caravan use.
Adaptors are available to convert from 13 Pin to 7 Pin single or dual function, or from 7 Pin to 13 Pin.


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Universal Electrics

Universal electrics are the most commonly used aftermarket method of fitting towbar electrics without the complexity and expense of a vehicle specific wiring loom. Fitment on more modern vehicles with Can-Bus wiring, can in most cases use a Universal By-Pass Relay kit for standard road lights etc. and for the 12S caravan electrics a split charge relay would be fitted in conjunction with your required socket choice.

Universal By-Pass Relay

Modern complex vehicle wiring and CANBUS systems now means that on many new vehicles wires can power more than one light at a time and the power system often works on a pulse system rather than a constant feed. These changes have meant a By Pass relay is required for most modern vehicles using universal wiring.
Fitting a relay does not provide the additional benefits provided by vehicle specific towbar wiring, for example with universal towbar wiring kits, parking sensors and fog light deactivation are not enabled.
The ‘Ryder’ By-Pass Relay which we supply or fit is compatible in operating LED towing lights.

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Caravan 12S Split Charge Relay

When a vehicle tows a caravan and the caravan is equipped with a 12 volt fridge or an auxiliary battery or both, it is necessary to provide a connection between the caravan and the towing vehicle to provide power to these.
When such a connection is provided it is advisable to protect the vehicle's own battery from being accidentally drained by the caravan fridge and auxiliary battery.
The usual way of providing this protection is to install a suitable relay or pair of relays which will turn off the connections when the vehicle's alternator is not running.
These are Smart Combi relays, and are switched on and off by an internal voltage-sensing system that senses when the vehicle's alternator is charging the vehicle battery.
It is absolutely essential that any such relay system should work reliably, fail safe, offer full protection to the battery, and, if possible, to the auxiliary battery as well.
The Smart Combi, self-switching combination relays from Ryder Towing make the installation of Caravan auxiliary wiring safe and easy, especially in the context of the complex electronics in modern vehicles.

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Vehicle Specific Wiring Looms

We are the sole importer and distributor for Right Connections UK who specialise in the development and production of vehicle specific towbar wiring kits used by towbar manufacturers and towbar fitting specialists.
We can supply a wide range of 7 and 13 Pin kits which when installed either interface with the vehicle using the original connectors and / or communicate directly with the vehicles managements systems. This enables the manufacturer’s towing safety features such as TPS (Trailer Stability Programs) now present on most modern day vehicles.

Since the early 2000’s, automotive technology moved rapidly forward in introducing network systems in vehicles which allowed the detection of a trailer. In many cases, not only did the manufacturer design the vehicle to detect the trailer, but created enhanced features within the network, which actually makes it vitally important for the trailer to be ‘seen’ and not ‘hidden’ from the towing vehicle. These include some important safety and stability features, along with convenience items such as automatic fog light cut-off and parking sensor deactivation.
Here are some of the related towing systems which your vehicle may have, which ‘NEED TO SEE’ the trailer when it is plugged in:
  • Brake electronics
  • Suspension system (ASS)
  • Engine electronics
  • Engine cooling system
  • Cruise control
  • Parking aids
  • Reversing camera

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