Bulb is fine, and its the blue light which is the running light, the yellow wire is for the brakes and that works fine.
with the headlight on it puts out about 0.3 volts, so obviously somewere in the loom there is either break or high resistance that is stopping the juice getting to the back light :S even on the plug straight out of the switchgear i am not getting anything above 0.3V volts, and the switchgear was brand new and working when i put it on there a week or so ago so its not that.
any more ideas? this one has me stumped O.o, i havent changed any of the wiring so im not sure why it would suddenly not work.
is there a regulator or something in the circuit that may be faulty?
and whilst im here, anyone know where i can find a wiring diagram for the complete bike and/or brake lamp circuit