If you put the system it test and everything sprays, then it should work in driving conditions if the grey harness is connected right and the yellow THRES light is coming on, on the control board.

You say you tested individually, but have you put the entire system in test (SYS jumper)? This fires the entire system at full spray. If this works then it would be narrowed down to the grey cable connections.

Are all the jumpers on the board still in the factory defaults? Is the gauge turned on? Are the adjustment pots still int he factory defaults?

I ask because you say boost but the HFS-3 by default is primarily IDC only.