In the UK, trailer lights are normallly connected using a 7 pin plug and socket known as a type 12N. If you look at a socket or plug you should be able to see the pin lables (1-7).
In some cases and more often in Europe the trailer light will be connected using a 13 pin plug and socket. If you have a 13 pin socket fitted to your vehicle, adaptors to plug in so you can use a normal 7 pin plug are available.
The table and diagram below explains the connections used on a 7 pin setup.
|Pin No.||Cable colour||Function|
|5||Brown||Right tail/side light (& No, plate lamp)|
|7||Black||Left tail/side light (& No, plate lamp)|