Electrics & Wiring Options
Types of Wiring: standard/universal or dedicated/vehicle-specific.
Single (7-PIN/12N) Electrics:
All the functions for the rear lights on a vehicle except for reverse. This is the cheapest option and is sufficient for cycle carriers, trailers and some caravan users (who do not require the supplementary 12S functions outlined below).
Twin (7-PIN 12N+12S) Electrics:
One 12N socket (identical to single electrics above), plus a second socket (12S) – mainly used when towing caravans. The 12S socket includes a permanent 12v power supply and a switched 12v power supply for the fridge, interior lights and auxiliary battery, it also contains a feed for the reverse lights on the caravan. Many people who only tow a caravan for a couple of hours and will then be pitching up at a caravan site with mains electricity opt to do without the 12S socket and just fit single electrics to their vehicle.
This is the new ISO standard socket being fitted to all new UK caravans sold from 2009, it covers all the functions of both the twin (12N and 12S) sockets. Designed to be waterproof, easy to fit/remove (twist operation) and with good fitting quality terminals that avoid any pin burnout or voltage failure. Being the same size as one 12N socket makes it ideal for detachable towbars as it can be more easily hidden than twin sockets (for those who require the supplementary 12S functions).
Types of Wiring
Standard (Generic/Universal) Wiring:
This is the traditional norm for towing electrics, it works by taking a small current signal from the vehicle’s lights to trigger a relay and send a direct power supply to the towing socket. It does not communicate with the vehicle and will not activate any safety or convenience systems. It does however isolate the trailer wiring from that of the towing vehicle, thus protecting the car’s wiring from damage should the wiring in the trailer (or cycle carrier) malfunction. It is a tried and tested system in very wide use. Bypass systems are found both in “universal/generic” (non vehicle-dedicated) systems and in dedicated and OEM (original equipment manufacturer) systems. Standard wiring is almost always the cheapest option, and often by a significant margin.
Dedicated (Vehicle Specific) Wiring:
For most vehicles standard wiring is the preferred choice given the higher cost of dedicated, however for many vehicles it is advisable to choose the latter. These include:
1. Vehicles with advanced towing/safety features e.g. TSP* or ACC** (see explanation below);
2. Vehicles still under warranty (check whether your warranty provider specifies a dedicated wiring requirement);
Please note: With dedicated wiring some vehicles will require re-coding at the dealer in order to activate TSP and PDC/Fog light cut-off – in the vast majority of cases we can do this here.
* Trailer Stability Program (to help reduce the ‘snaking’ tendency of a trailer).
** Adaptive Cruise Control (increases breaking distance between vehicles when towing).