Types of socket
7 pin socket (12N)
This socket is a standard 'single electric' point which is required for most trailers and cycle carriers.
The functions it provides are indicators, tail lights, brake lights and fog light.
Twin 7 pin sockets (12N & 12S)
These sockets, known as 'twin electrics' are usually fitted if you are towing an older caravan.
The 12N (black) provides the road light functions and the 12S (grey) provides a reverse light feed, runs the fridge in the caravan and charges the battery whilst you are travelling.
13 pin socket
This socket is mainly used for newer caravans as it combines the two 7 pin 12N & 12S into one socket for convenience. Most modern caravans have a 13 pin plug.
This socket can also be required for some bike racks and some new trailers. The advantage of this is the ability to have a reverse light on the trailer which is not standard with the traditional 12N 7 pin socket.
Towbar Electric Kits
Vehicle specific electrics
A vehicle specific wiring kit connects into the existing wiring loom on the car. It is the equivalent to the kit a main dealer would install if they fitted the towbar.
These kits are not necessary on every vehicle, however we usually recommend this kit is fitted if the vehicle is still under manufacturer's warranty or if it has any built in towing related features such as Trailer Stability Program which are only activated by using this kit.
Bypass relays are used on some vehicles to protect a circuit from overload or to avoid confusing the bulb failure monitoring systems.
They take a signal feed from the vehicle's circuit and power the trailer lights using a separate power supply, usually from the battery or fuse board.
A built in buzzer connected across the indicators gives an audible confirmation that the indicators are working correctly on the trailer.
A bypass relay does not activate towing features in the same way as a vehicle specific kit.