wishing i was more familar with how the busa wiring is set up...
but ultimaly you can work in 2 directions...
1.. continuity from the bulbs back... posivitive and negative. every single wire in the curcuit.
SAFER doesnt blow fuses
2. VOLTS. positives and grounds. from the battery all the way to the bulbs...
may blow a fuse or two messing with test leads(paper clips)
trouble shooting tip of the day:
if the wire is coming from, lets say, cdi, rectifier, something you dont want to cut open just to test,
use a safty pin to poke thru the wire and this gives you a test point. if you going to keep using the test point close the safty pin and keep there till the testing is completed(watch for blown fuses)
good luck.. again wishing i was more knowlegeable about the busa wireing set up..