ISO 11446 details the connections and standards used in the 13 Pin Trailer connector. The connector was developed in the late 80’s by Erich Jaeger as the demands of the automotive industry required additional electrical circuits to be connected to trailers. They are sometimes known as “Jaeger” connectors – especially in Europe.
ISO 11446 is broken into two parts:
- ISO 11446-1 13-pole connectors for vehicles with 12 V nominal supply voltage not intended to cross water fords.
- ISO 11446-2 13-pole connectors for vehicles with 12 V nominal supply voltage intended to cross water fords.
The standard title always identifies the year and revision in its title:
The above is decoded as Standard 11446 Part 1 dated 2012 revision 05. If it is ‘draft’ or ‘proposed’ it will always state this after the revision number.
The current standard specifies the following pin allocations (the table is exactly as per the standards document):
(You can click on the above table to open it full size)
When ever you are having a tow bar fitted with towing electrics it is important that you always choose either ‘OEM’ (electrical kit produced by/for the vehicle manufacturer for your specific vehicle) or “vehicle specific” (electrical kit produced by an independent supplier specifically for your make and model of vehicle) and check it is fully ISO 11446-1:2012 compliant. It is not recommended to install a “generic” electrical towing kit that is simply wired into the vehicles electrical system. Although it will seem cheaper at the time, in the long run it could cost you a lot more in revisiting the installer and fault-finding. In fact most manufacturers now state that installing a non manufacturer approved electrical towing kit will invalidate any vehicle warranty and could compromise any on-board vehicle electrical safety systems.
Unfortunately some vehicle manufacturers (OEM) and vehicle specific electrical towing kits are not fully compliant and do not include connections for the fridge (Pin10) of charging the leisure battery (Pin 9). Notably BMW, Audi and Volkswagen seem to produce kits that are not fully compliant.
Additionally if you have an independent auto electrician install a towing electrics kit, you must ensure that it is fully compliant with the ISO standard AND the vehicle manufacturers specifications – which could include a software update to the vehicles ECU so that the vehicle on board systems (ESP, ABS & Trailer Control) are activated and functioning correctly.
Some vehicles use the trailer grounding Pin 12 to signal to the vehicles ECU that a trailer is connected. The ECU uses this information in various ways – to change the ABS settings, alter the ESP programme and mute the reverse sensors (if fitted) along with on some vehicles turn off the rear fog lights on the vehicle. It is important then that you do not make any modifications to the trailers electrical system that affects the ground connection between Pin 12 and Pin 3 on your trailer. (NOTE: some pre 2012 caravans/trailers that use the 13 pin plug will not have implemented this, if you have just changed to a new tow vehicle, it is worth checking if your vehicle needs this and that the caravan/trailer is suitably wired).
Some vehicles do not use pin 12 to detect if a trailer is connected, they detect the presence of a trailer by sending signals via the CANBUS system to detect if trailer lights are present on the 13 pin towing socket. Its worth finding out how your vehicle detects the presence of a trailer.
Because of Copyright rules on the official standards document, I cannot reproduce it here in full and if you want a copy you have to pay nearly £100 for all 14 pages of it. I can understand making some charge – say around £5 to £10 for an electronic version, the current charges though are just silly. However I hope the above gives you enough information.