uk.pg.photos.yahoo.com/ph/kitkat … pg&.src=ph
you might need to enlarge it to read it.
I cant read it Jim, but it looks like important stuff, is it available anywhere else?
The essentials are repeated here - http://www.vosa.gov.uk/vosa/publications/iso%20cable%20leaflet.pdf
Cheers Petrock, a nasty business.
The use of ISO7638 connections became law from May 2002
where the tractor and trailer are both provided with connections.
Always have them connected
Is this cable a secondary cable for ABS braking systems? There are a few trailers here in the US that use just such a system, but most ABS trailers here have a self-contained unit on the trailer. Are you guys over there hooking up 2 cables on newer trailers?
You have your Red Airline, Yellow Airline, two electrical cables and the ABS lead, 5 in total 
and sometimes a sixth cable for charging of tail-lift batteries.
Taillift Batteries 
The sixth lead is to power the taillift from the unit batteries on the trailers in my depot. Never seen a tailliftt with its own power pack on board but I live and learn. 
All of our tail-lift trailers have their own batteries; they have all been like that for as long as I have been associated with the company which is over 20 years. They are either mounted between the landing legs or behind the rear axle. There is a split charging system fitted to the units and the trailer batteries are kept charged while you drive and that is what the extra lead does, it’s a three pin lead. There is also a socket on the headboard and we carry a set of leads which we can use to connect direct to the unit batteries in case of failure of the trailer batteries.
I’ve driven a trailer with a self-contained tailgate battery. Most here are like that.
In all my years driving, I’ve only ever seen 3 or 4 trailers that required a second electrical connector. Most only use the single connector which has something like 10 connections. This type of connector is universal in North America, required by US law, just like the air “gladhands” are.
I have driven artics where the tail-lift batteries are charged through the secondary electrics cable. Most of them though where powered by a short heavy-duty pair of cables with a cow-bell on each end. There is a permanent connection already set up to the vehicle battery, with a cow-bell connection fitted to the grab rail (or somewhere else, hopefully in easy reach). The trailer obviously also has a cowbell connector fitted to the front. The driver connects up to the trailer then the unit with the short set of heavy duty cables, only whilst using the tail-lift. When you finish with the tail-lift you disconnect the cable and put it back in the cab.
There is usually also a spare set of longer cables in the workshop, with heavy-duty crocodile clips on one end and a cow-bell on the other. This is for when a driver forgets to disconnect the normal set and drives off. At the first sharp corner, the cowbell gets pulled off at one end, usually rendering them useless. One of the grease-monkeys gets sent out with the spare set. If he’s in a good mood, much mickey taking is then given, if he’s in a bad mood 
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I know, I’ve made that mistake as well 
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Well I live and learn (oops said that already). Have to keep an eye out for that type of trailer.