12N Towbar Wiring Kit Fitting Instructions - Ryder Towing Towbar 12N Wiring - General guide Before you start. Examine the car carefully to see that all electrical circuits are working correctly and that no warning lights are showing. Take into account: With many modern cars it is best to take power from a source such as the bus bars at the back of the fusebox.[PDF] WIRING A VEHICLE FOR TRAILER TOWING - The Caravan Club TOWBAR WIRING This leaflet is prepared as a Club service to members. Some previous versions of it were titled ‘Wiring a Vehicle For Trailer Towing’. The contents are believed correct at 7 pin 12N wiring diagram. - Towing and Trailers Towbars Towbar wiring Towbar Accessories Information New to this website Special offers Commercial Body Fabrication Opening times Trailer Hire; 7 pin 12N wiring diagram. 12 N type plugs are used for road lighting only. This is currently the most popular plug used for towing as it does the lighting on most trailers and caravans.