I've lost spark in the Fury. It's got FAST efi which also controls the spark.

Lean burn dizzy connects to the ECU
ECU uses the white trigger wire to talk to the MSD
MSD fires an accel supercoil

I have power to the MSD box and the ECU during both start and run (verified)
When I use my test light on the white trigger wire, I hear either the pickup or the coil making noise and a test spark plug will arc. I get no spark cranking the engine over or when I release the key to the run pos.

Since I get spark to the plug when I ground the trigger circuit, is it safe to assume the problem is in the trigger portion of the circuit (i.e. when I short the trigger the MSD box, coil, wires seem to do their jobs).

If so, how do I test the guts of the dizzy?