td5 trailer brakes help

[disco63]

I'm trying to wire up a brake control unit in the td5 disco,(i did it in my old tdi 300) this unit is an in car type which i mount on the front of the d/s coin holder.I've managed to drag the wire from the engine bay through the cabin to the rear. Now having removed the d/s rear indicator assembly looking for a grommet to poke the wire through, i found the connection plug for the existing trailer plug . I know this because the plug and harness has a sticker on it stating "trailer plug harness" or something to that effect. which happens to have a blue wire (for trailer brakes) sitting there ready to go. So after all that, the question is, can i use this wire?
how do i get power from the cold side of the brake pedal to the control unit , is there wiring under the dash board ready to do this?
I don't have workshop manual for the td5, so i'm a little stuck as what to do
where can i get a workshop manual?

[LandyAndy]

Hi Mate
Cant help with the wires.
You can get the electronic manual(RAVE CD) from AULRO,click on markets up the top of the page.
Cheap,sales support the site.You just print off the page you need then head for the shed.
Andrew

[Graeme]

On my CD it shows the blue wire at the trailer plug is for fog lights.

[DEFENDERZOOK]

i think you will find the blue wire is a constant feed.....+12v.....
it can be used for running some accessories in a caravan for example......things such as 12v lighting......or a fridge......
nothing that draws high current though......


just hook up a set of digital multimeters to it and see what you get.......
the wire you need may be hanging there ready......

if you need a signal to let trailer know when the brakes are on.....take a feed off the brake lights......

im not sure how the electric brakes work as i have never had anything to do with them.....