Electic Fan Setup Help.... SNiper EFI

[elks]

So I have been running an electric fan relay that used signal directly from the temperature sending unit to turn on and off. However my new holley EFI system allows the touch screen to control temp setting etc. As such I would like to switch over to having the EFI control the system...

What I understand is that the EFI system is a ground based system. When the temp reaches the set point the computer grounds the relay turning it on and firing the fans.

What I do not under stand or know is how do I get from using sensor voltage to doing this ground style?

I have searched but do not think I am using the correct terms?

My current system Has Purple Wire to Power Fans. Red Wire to Bat+ Black to -, Yellow to ignition and Grey to sending unit. Can the grey wire be used and ran that way?

Thanks a bunch