Anyone got a wiring diagram for a tow bar?

Just picked up a tow bar from the local scrap yard and haven't got a clue where the wires or pins go.

I haven't got anything to plug into it yet so a pin diagram or wiring diagram would be great.

Just need a car trailer now for my MNR down to the SVA test and a track day to shake it down

Thanks,
Steve

Here . Caravanners to the rescue

Or here www.rydertowing.co.uk/trailer_towbar_wiring Another caravanner to the rescue!
Cheers, Pewe

A handy tip is to use the "foreign" 13 pin plugs. Makes it more difficult for someone to nick the trailor whilst your pride and joy is aboard.