Awesome, that makes perfect sense, thanks.
So the one with the big rubber cover is for the CTS for the ECU?
If I am reading this correctly the fans operate independently of the stock ECU?
So, assuming the rad. temp sensors work, I could just let them do their own thing? Or, if the SDS unit sends a ground signal (I believe it does, don't have the diagram handy) I could use the SDS fan control wire to run the main fan and let the secondary run off of the stock temp. sensor?