Trailer Wiring

7 Pin Lighting Connections (12N)

Trailer lights in the UK are normallly connected using a 7 pin plug and socket known as a 12N using a black cable. 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 we have an adaptor to plug in so you can use a normal 7 pin plug.

The table below with the diagram explain the connections used on a 7 pin setup.

Diagram of a 7 pin trailer plug
Pin Wire Colour Function
1 Yellow L/H Direction Indicator
2 Blue Rear Fog Lamps
3 White Earth Return
4 Green R/H Direction Indicator
5 Brown R/H Tail & No. Plate Lamp
6 Red Stop Lamps
7 Black L/H Tail & No. Plate Lamp


Notes for 12N Wiring

Number plate lights on the trailer should be wired to avoid common contact between pins 5 & 7 of the 12N socket.

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Categories: Trailers and Trolleys