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What is a 12N connector on a car?

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.

What does it look like?

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.

What is a 12S connector on a car?

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.

What does it look like?

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.

What is a split charge relay?

The relay splits the power supply from the vehicle to the 12S connector.

Why is the relay needed?

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.

What happens to the split charge relay when I start my engine?

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.

What happens to the split charge relay when I start my engine?

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.

 
What happens to the power from pin 4?

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.

 
How can I tell if my caravan has this facility?

All caravans built from September 1998 should have this facility. Most caravans built before then use pin 2 as a battery charge supply.

 
What is a 13 pin connector?

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.

 
What does it look like?

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.

 
Can you use 12N or 12S sockets/plug with 13 pin?

12N and 12S is not compatible with 13 pin, however adaptors are commercially
available to interchange between both systems.

 
Is there a system that uses both 12N and 12S functions in one socket?

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.
 
How can I tell if the towing electrics are operating correctly whilst driving?

The electrical kit for your vehicle will have a tell tale supplied which will inform the driver of an indicator failure.

 
What is a tell tale?

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.
 
How often should I check my caravan/trailer lights?

A full light function check should be performed every time you connect.

 
What happens if a brake bulb fails on the trailer?

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.

 
What is a fog lamp ‘cut out’?

This disables the vehicle's fog lamp when towing to reduce reflective glare from the caravan/trailer.

 
Do all cars have a fog cut function?

Some wiring kits have this function as standard otherwise you may have to request this at installation.

 
Can I fit the electric kit to my own car?

Modern electric kits come complete with instructions, if you have any doubts you should always employ an approved stockist to install your electrics.


What happens if a bulb fails on the car?

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.  

Other questions

If your questions have not been answered on the site please contact our after sales department who will be able to answer all your questions about towbars, wiring kits and fitting.

Telephone: +44 (0)1254 232808

E-mail: customercare@advancedtowing.co.uk