So I'm full bore into this custom electric fan set up and close to getting it. I have a fully built 6.0, i have 4-12" 2500 CFM cooling fans, with a two stage stand alone temperature controller w/ each set having its own relay set-up, i have upgraded the electrical system to a 320amp system to carry the load of the fans. Now this is where it gets tricky and need some answers. I know disconnecting the fan clutch all together will throw off the PCM. So I want to utilize the fan clutch plug if possible. Is the 5v reference just a positive feed back for the PCM to know that particular sensor is good or does it command and relay information. Also I haven't checked yet because I haven't put the battery's back in but does the 5v reference come from the PCM for from the fan clutch/(sensors) cause it would kind of be determined by the first question. Another thing is if i connect the fan control speed wire to the relay to activate 1 set of fans in theory if i use a resistor on the same line for the 2nd set of fans slightly out of range of were the control wire sends the 1st signal and if the truck does not cool off and it this the second range the will supply the voltage needed to activate the 2nd stage of cooling fans.