easiest way to get the wiring diagram is in scrappy.look at another micra and note the wiring colours going to the block and then check they correspond to yours.
for the relay,off top of my head i cant remember if the relays on fuse panel at your right knee,or the one beside battery.something tells me its the fuse panel at your knee.so easy way to find it is to remove the cover and place your fingertip over each relay and flash the fullbeam.when you find the right one youll feel the click through your finger.
hope this helps