Its simple if you know which the fuses are. You can use a meter or rig up a 12v bulb with a couple of wires: Take out the fuse and turn on the lights
Put one lead into one side of the fuse and the other to earth. Do this to both sides of the fuse recess. You should get a reading from one side. If you do, turn off the light and the reading or light, if you usea bulb, will go out. that will tell you that the switch is working and should be going through the fuse if that is ok.If you get no reading then try the wire coming from the switch Should be the same colour. If no reading then it is the stalk switch.