However, I'm not 100% sure they actually do fit '01-'03 cars, so if anyone knows please post below - ta
It works like this:
Terminal 30 has a 12v battery supply to it via an in-line 15a fuse(not shown ) I went straight onto the battery.
Terminal 85 has the constant 12v feed from the cars original h/lamp plug (Yellow/Red) and is then connected to one side of the dip beam bulb (outer headlamp) the other side of that bulb must be attatched to earth.
Terminal 87 goes to one side of the main beam bulb on the inner headlamp and the other side of that bulb is connected to the Red/Blue on the cars original plug, as this is a switched earth when main beam is selected.
Terminal 86 is connected to earth.
So when dipped beam is selected, the yellow/red is then live and feeds the dip bulb as well as feeding the relay at terminal 85, through the relay to 86 thus energising it.
Because the red/blue is actually live whilst dip is selected, the main beam bulb won't light up with the power supplied from terminal 87, but when main beam's selected, the red/blue wire is now earthed and the main bulb lights up.
Apologies for the poor drawing, I find it much easier to actually do the job than try to show on here how to do it
Edited because the original drawing wasn't strictly accurate - apologies