These later system 11 flasher circuits can be a little tricky. Notice in the solenoid table posted above that the flasher circuits only light up when the 'c' side of the relay on the aux driver board is enabled. So unlike most coils, you won't get voltage at the flashers when they are not being used. The full wiring diagram for the machine is not listed on the ipdb.org, but if you have a hard copy, I bet there is a wiring diagram that shows all the coils and flashers in relationship to the aux driver board. I would start with that diagram, and trace the wiring from the Aux power board, to the interconnect board, and finally to the flasher. Eliminate problems with the wiring before you start poking around with the boards themselves.