I have bought a USB adapter to replace the cigar lighter in the front of my mk4 1.8 tdci 57 plate mondeo  I have managed to remove the old one but I'm presented with 3 wires  two in a L shape one side is brown and white the other is black and white with then there is a separate wire in brown that I think just goes to the light on the old socket  my new socket just has a red and black wire for it.  The red wire has a fuse built into it so I assume it live

 

I need to know which out of the ford's cables is live and which one is neutral and if the third cable needs attaching or can it just be left

Use a voltmeter to check ( in my opinion that is essential for any electrical work but you could possibly use some sort of low wattage 12v bulb instead).    One of your 3 wires will be permanently earth (- connection on battery) one will be live most of the time (except when the anti flat battery circuit turns it off).  The third will only be live when the panel lights are on. sounds like you only need the first 2. If you aren't going to connect the  wire for the lighting you need to ensure it cannot short against anything else by insulting it properly.

The third cable is a live feed from the headlight control for illumination.

On the L shaped connector the terminal that goes to the centre pole of the original 12v socket is the live and the one to the side pole is earth.

Sent from my SM-G900F using Tapatalk