To be honest, I simply left the 3-pin fan connector that came with the FM-17 alone and figured it was meant to work like that. I did not know which wire from the flowmeter went to which wire in the plug either and guessed 50/50 chance. It worked and left it alone.
I then later determined that it was only sending impulses and figured it did not really matter in the end. The amplifier board that comes with the FM-17 multiplies the impulses by 10. The impulse value of 197 is correct for this flowmeter with the Aquaero.
More discussion on the wiring here:
http://www.realredraider.com/vbulletin/showthread.php?t=5821