We had a problem with the fridge not working when towing, also the lights on the caravan would work on one side and not the other, or if the lights all worked the indicator light to flash too quickly also causing the side light to flash.
We checked the tow vehicle and found that everything was in good order, so we checked the 7 pin N&S plugs on the caravan. As you can see from the photos these were in poor condition. Some of the coloured wiring sleeves (not shown) was also split exposing the copper wire.
In this photo you can clearly see that the centre pin on the S plug has melted. We changed bot the 7pin N and 7 pin S plugs, making sure these were wired up correctly. This took about forty five minutes to change both and hooked them up to the towing vehicle to check that the fridge and lights worked properly. This small job has resolved the issues we had been experiencing.
The wiring diagram for the 7 pin N plug
Pin 1 Yellow - Left Indicator, Pin 2 Blue - Fog Light
Pin 3 White - Earth, Pin 4 Green - Right Indicator
Pin 5 Brown - Right Tail/Side Light, Pin 6 - Brake/Stop Lights. Pin 7 Black - Left Tail/Side Lights
The wiring diagram for the 7 pin S plug
Pin 1 Yellow - Reversing Light, Pin 2 Blue - 12v ignition on (Battery Charging), Pin 3 White - Earth Terminal for 2 and 4, Pin 4 Green - 12v Permanent (Direct from Battery),Pin 5 Brown - Reversing Sensor (Usually spare), Pin 6 Red - 12v ignition on (Fridge), Pin 7 Black - Earth Terminal for 6
Pictures for the wiring diagrams have been taken from www.uk-trailer-parts.co.uk.