Caravan 12S 7pin socket & plug wiring
from Western Towing – www.westerntowing.co.uk
This is the standard UK wiring of a the supplementary socket and plug otherwise known as 12S. There have been slight variations over the years as most newer caravans control the battery charging in the caravan rather than from the towing vehicle. The earth return is also a more recent addition as it used to be spare but since caravan fridges have got larger it was necessary to provide a separate earth return for the fridge. The diagram below shows the view from outside the vehicle socket (under the flap) and from inside the caravan plug.
| Terminal Number | Function | 7 core wire colour |
|---|---|---|
|
1
|
Reversing Light |
Yellow
|
|
2
|
Positive Ignition key ON (Battery Charging) |
Blue
|
|
3
|
Earth |
White
|
|
4
|
Positive direct from battery |
Green
|
|
5
|
Reverse Sensor (Optional), usually spare |
Brown
|
|
6
|
Positive Ignition key ON (Fridge) |
Red
|
|
7
|
Earth return for Fridge (Terminal 6) |
Black
|
The normal light socket or plug 12N diagram and wiring chart can be found here
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