Question: LS3 fan control wire; power or ground?

[Gmachine1911]

I’m looking at purchasing the Entropy fan controller but I do not want to run their secondary temperature sensor. On my LS3 crate engine with the GMPP harness, does the single blue fan wire send 12 V or a ground signal? I’m sure. this has been covered in depth already but after numerous searches, it is evading me. Thanks!