if you have the switch with you now, look for a GREY AND RED wire, or a GREY AND BLACK WIRE. either of these will be a switched positive for your headlights... then just wire red wire on new light to this and black wire on new light to earth... or on the switch the BROWN wire

GOODLUCK
 
Back on topic :lol:

You're best off grabbing the multi-meter and bell out the wires behind the light switch to find the lighting feed. I'd go do it for you but the battery on mine is so flat it wont charge anymore :(