The Normal power required by the caravan/trailer for indicators, brake, fog and sidelights are provided via the 12N connector. This is a socket on the vehicle and a plug on the caravan/trailer.
The socket cover is usually coloured black and houses 7 pins which are numbered 1 to 7. The plug is also black and has a slot that locates opposite the cover hinge of the socket. The central contact (number 7) is female in the plug.
The 12N connector needs to be connected using the correct wiring according to DIN/ISO 1724, pin connections as in the following table and picture::
12N seven core cable has a black outer sheath. Each of the seven wires within should be around 0.65mm² and sometimes a larger earth wire at 1.0mm². They are usually colour coded as in the previous illustrations.
No, some dedicated and original equipment kits use the wire colours specific to the vehicle manufacturer.
The Supplementary power required by the caravan reversing lights, interior lights, battery charger and fridge are provided via the 12S connector. This is a socket on the vehicle and a plug on the caravan/trailer.
The socket cover is usually coloured grey or white and houses 7 pins which are numbered 1 to 7. The plug is also usually grey or white and has a slot that locates opposite the cover hinge of the socket. The central contact (number 7) is male in the plug.
The 12S connector needs to be connected using the correct wiring according to ISO 3732, pin connections as in the following table and picture. Please note; Make sure that when you wire the 12S socket you independently earth wires 3, 5 & 7 to the car. If the split charge relay in the car allows it, connecting the blue wire from pin 2 to the second switched output terminal will ensure compatibility with pre and post 1998 caravans.
12S seven core cable has a grey outer sheath. Each of the seven wires within should be around 1.5mm² and a larger white earth wire at 2.5mm². They are usually colour coded as in the previous illustrations.
The relay splits the power supply from the vehicle to the 12S connector.
To avoid a flat battery on your vehicle the relay isolates the caravan from the vehicle when the engine is off apart from a permanent supply to the caravan interior lights through pin 4.
When the engine is running the relay will provide power to pin 4 and also pin 6 for the fridge and if wired for pre 1998 caravans pin 2 for the charge circuit, this can also be used as an extra power feed for larger fridges in post 1998 caravans.
Modern caravans have a built in relay that switches this power when the engine is running from the caravan interior lights to the charge system for the caravan's own battery.
All caravans built from September 1998 should have this facility. Most caravans built before then use pin 2 as a battery charge supply.
Some vehicles or caravans may come equipped with one single connector that incorporates both 12N and 12S functions, this is known as a 13pin or continental type connector.
The socket is usually coloured black and houses 13 pins which are numbered 1 to 13. It also incorporates a twist lock mechanism that secures the plug to the socket.
The 13 pin connector needs to be connected using the correct wiring sequence according to UK an European specifications as in the following table and picture. Pins 1 to 8 usually use 1.5mm² wire and pins 9 to 13 usually use 2.5mm² wires.
12N and 12S is not compatible with 13 pin, however adaptors are commercially available to interchange between both systems.
The West 13 pin socket looks like a standard 12N 7 pin socket but includes extra pins between the standard 7 pin configuration so either a standard 7 pin 12N plug can be used for a trailers and light boards or the specific West 13 pin plug for caravanning.
The electrical kit for your vehicle will have a tell tale supplied which will inform the driver of an indicator failure.
This is a device that tells the driver that the indicators on the trailer are operating correctly. It can be an audible beeper or a dash mounted warning light that operates in time with the indicators and stops if an indicator fails. Some will only operate if an indicator fails on the trailer others notify the driver of indicator failure by making the vehicles own indicators flash at a faster rate.
A full light function check should be performed every time you connect.
Ordinary electric kits will not register this however with some dedicated kits a message will appear on the dash (model dependant) to warn you of the failure.
This disables the vehicle's fog lamp when towing to reduce reflective glare from the caravan/trailer.
Some wiring kits have this function as standard otherwise you may have to request this at installation.
Modern electric kits come complete with instructions, if you have any doubts you should always employ an approved stockist to install your electrics.
In most cases the lights on the caravan/trailer will still operate, the bulb should be replaced as soon as convenient. If the vehicle has bulb failure monitoring, multiplex or CAN bus wiring, you may be notified of a bulb failure, this is model dependant.