Today I set about swapping out the twin 7 pin tow connectors for a single 13 pin one. Obtained the following from Screwfix with nice easy screw terminals and pin outs.

https://www.screwfix.com/p/maypole-mp129-13-pin-european-trailer-board-socket-w-gasket-12v/48923

I have connected up as follows... (Edited to correct mistakes)

As Follows,

13 Pin Number - Colour of LR Wiring Loom - Description of Control - LR wiring in car.
RH Light Cluster Wiring
Pin 1 - Yellow - LH Indicator - Green/Orange
Pin 2 - Blue - Rear Fog - Orange/Yellow
Pin 3 - White - Earth Return - Black
Pin 4 - Green - RH Indicator - Green/Yellow
Pin 5 - Brown - Right Tail Light and Number Plate - Red/Black
Pin 6 - Red - Brake Light - Green/Purple
Pin 7 - Black - Left Tail Lights and Number Plate - Red/White
LH Light Cluster Wiring.
Pin 8 - Yellow (Grey 7 Pin Cable) - Reverse - Green/Brown
PIn 9 - Green (Grey 7 Pin Cable) - Power Supply Steady - White/Orange
Pin 10 - Red (Grey 7 Pin Cable) - Power Supply Switched - Pink/Orange
Pin 11 - Black (Grey 7 Pin Cable) - Earth Return (Contact 10) - Black
PIn 12 - Blue (Grey 7 Pin Cable) - N/C - N/C
Pin 13 - White (Grey 7 Pin Cable) - Earth Return (Contact 9) - Black

Tested and almost all working ok. The reversing lights not working (Edit : Fixed). This turns out that none of the 7 pin connectors are working (Edit :Fixed). On inspection both cables go up the right hand wheel arch! The 7 Pin Aux one should go up the left hand wheel arch behind the CD changer. Both the cables were run and very close to the exhaust so thats not a good idea. I have now re-routed the grey aux cable to the left hand wheel arch and will wire in tomorrow. Annoyingly I cut the grey cable down by 15cm when I fitted it first off. Now its really short but will reach.

Does anyone have a correct wired system? I need to know the following connections in the car, there is a loom with a bare un-used connector with the following. Edit: Thanks Gilbertd

Left Hand rear wheel arch...
Orange/White - Ignition Switched Live
Pink/Orange - Permanent Live
Green/Brown - Reversing Lights
Black - Ground.

RH wheel arch

Green/Orange - Left Hand Indicator
Black - Earth Return
Red/Black - Right Tail Light and Number Plate
Orange/Yellow - Rear Fog
Green/Yellow - Right Hand Indicator
Red/White - Left Tail Light and Number Plate
Green/Purple - Break Light

I am guessing I am going to have to run a feed from the battery to the Red Switched connection if I want to run the fridge in the caravan when towing. (Edit - No you don't need to.)

If you look behind the LH rear light cluster you'll find an unused 4 way connector. That has permanent live, ignition switched live, ground and reversing lights on it. I've used it to pick up power for a pair of cigarette lighter style sockets in the boot for keeping stuff charged up.

Colours are:
White/Orange, Ignition switched live
Green/Brown, Reversing lights
Pink/Orange, Permanent live
Black, Ground

Thanks Gilbertd, I did indicate that I have found that connector thanks for highlighting what the colour codes are for.

I presume if I want to run a live feed via a relay to run the caravan fridge when the engine is running I need to run it from either the battery or the BECM, places online have said that you can run it from a spare point on the BECM and ground it to chassis locally.

The White/Orange wire comes off fuse 8 at the BeCM which is a 30A fuse and it's switched by a relay within the BeCM itself, so you may as well just use that for the fridge if you want it only powered when the engine is running. Or, use that to power a relay and switch the permanent live from the Pink/Orange if you are concerned that the current draw may be too much. The Pink/Orange is fused at 20A but as it also supplies other items, RAVE says that it is capable of supplying 10A to the trailer socket.

Excellent, I am going to tow the caravan to north swindon next weekend as working there for a week. Main thing was reversing lights working, if I can't get the fridge to run on 12v then I can sort that at a later date.

You mention that the White/Orange can carry 30Amp is that switched with ignition, and if it does draw too much would it do any damage to the BECM?

I will check tomorrow but always nice to know in advance.

So wiring would be as this..

Orange/White (Ignition Switched Live) - Power Supply Switched - Red
Pink/Orange (Permanent Live) - Power Supply Steady - Green
Green/Brown (Reversing Lights) - Reverse Light - Yellow
Black (Ground) - Earth Return (For Power Supply Switched) - Black and Earth Return (For Power Supply Steady) - White.

As well as the supply to the trailer socket, that fuse supplies, the radio, aerial amp, HEVAC and cigarette lighter socket. It is switched by a relay in the BeCM and I doubt the relay is rated at less than the fuse so even if you do overload it, the fuse should pop before you do any damage. What does the fridge draw?

its around 8-12 amps at 12v. hence why I don’t want it live when the engine isn’t running!

Just been out to get the manuals and the leisure battery is not taking charge, great another thing to fix tomorrow.

All wired and tested working fine.

Please note my original wiring write up above was incorrect (I have now changed it), if you have already started you are going to get weird things with the indicators.

This is a very simple job and could be done for pennies.

Hope it helps and thanks for the assistance again guys.