Tuesday 9th May 2023
Trailer Wiring Diagrams
One of the most important parts of fitting a towbar to your vehicle is connecting the electrics from the towing vehicle to the trailer or caravan that you are towing. The electrics are required to power the lights on your trailer and, if you own a caravan, the internal electrics inside the caravan, therefore it is important to ensure that it is done correctly. To help make sure your electrics are working properly, we've also designed a one-person, handheld electrics tester to make your job quick and easy! Depending on the type of electrics your trailer and towing vehicle have, the wiring inside will be slightly different. All pins are marked inside and can only be assembled in one way. Below we have the wiring diagrams for both a 7 and 13 pin connector. You can also watch a video where Glenn explains how to wire a 7-pin plug here.12N Type 7-Pin Wiring Diagram
The 12N towing electrics (also known as single 7-pin electrics) are needed to run the lights on your trailer, caravan, or other towable equipment. The single 7-pin operates the left and right indicators, tail lights, sidelights, fog light and brake lights.
| PIN NO. | COLOUR | FUNCTION |
| 1 | Yellow | Left hand indicator |
| 2 | Blue | Rear fog lamp |
| 3 | White | Earth |
| 4 | Green | Right hand indicator |
| 5 | Brown | Right hand side / tail lights |
| 6 | Red | Brake Lights |
| 7 | Black | Left hand side / tail lights |
12S Type 7-Pin Wiring Diagram
The 12S type 7-pin electrics (also known as twin electrics), is a 2 plug system that combines the single 7 pin 12N electrics socket with a 12 S socket. The 12 S sockets are used where you need more power than what a single 7 pin socket can provide. The 12 S type will power everything that the 12 N does, including fog, brake, and sidelights, plus any internal caravan electrics such as fridges and interior lights.
| PIN NO. | COLOUR | FUNCTION |
| 1 | Yellow | Reverse light |
| 2 | Blue | Battery charging (switched live) |
| 3 | White | Earth |
| 4 | Green | Interior lights (permanent live) |
| 5 | Brown | Spare |
| 6 | Red | Fridge (switched live) |
| 7 | Black | Earth |
12V 13-pin Wiring Diagram
These are the most modern style of trailer electrics (all EU caravans post-2008 are fitted with 13 pin electrics as standard). This type of electrics is essentially a 2-in-1 socket that has all the capabilities as the twin electrics system in one socket rather than the two separate ones. They are more adaptable for detachable towbars as well. If your trailer or caravan has 13-pin electrics on it but your towing vehicle has 7-pin electrics, you will need a converter to connect the two.
| PIN NO. | COLOUR | FUNCTION |
| 1 | Yellow | Left hand indicator |
| 2 | Blue | Rear fog light |
| 3 | White | Earth (contacts 1 to 8) |
| 4 | Green | Right hand indicator |
| 5 | Brown | Right hand side / tail lights |
| 6 | Red | Brake lights |
| 7 | Black | Left hand side / tail lights |
| 8 | Pink | Reversing light |
| 9 | Orange | Permanent live |
| 10 | Grey | Switched live |
| 11 | White/Black | Earth for contact 10 |
| 12 | White/Blue | Coding for coupled trailer |
| 13 | White / Red | Earth for contact 9 |
Published 26/04/2021
