I guess I skipped over the data line part of the thread. I thought it was just a matter of adapting high and low pressure switches and sending signal to the pcm, my bad. It just seems wasteful to me to have the fans on high when your on the hi-way cause all thats doing is slowing down air flow. I bet relays could be directly wired to pressure switches for a little more control over the fans, I think some old school switches are even adjustable.