1997 Chevy Venture Temperature sensors

1997 Chevy Venture

I'm trying to debug a cooling system problem. My radiator cooling fans don't seem to be switching on when they should.

I assume that there's a temperature sensor somewhere that (through the computer?) Tells the cooling fans to switch on.

Then there's obviously a sensor whose reading is being displayed on my dashboard temperature gauge.

Are these the same same ECT sensor? Or is a seperate sensor doing each of the two tasks?

Any clue where they may be located? (I believe I've found one near where the upper radiator hose meets the engine block.)

Thanks so much!