Cooling Fan Circuit on late ST ECU

[s24a]

Have a question about how the cooling fan circuit on the late (89661-1A190) ECU used on 93.5 and up Silvertop Manual trans engines works.
The fan switch seems to be a normally "closed" switch which opens above a temperature (~92ºC).
It runs through the AC "trinary" pressure/temperature switch found on the AC line and into the ECU on pin "N1" of the 26 pin ECU connector. As I am not using AC, I will not use the trinary AC fan control or the AC computer.

But since this is a normally closed switch, how is the ECU handling this signal? Does the ECU source a 12V? signal to the switch which the switch grounds, and then when above the trigger temperature when the switch opens the ECU then sees the voltage and can adjust the idle for the fan, or is it also going through a relay coil to actually control the function of the fan as well as idle adjustment?

I am starting to build a wiring harness and if this circuit does control a relay, it will make a difference in how I design the harness.

Any assistance here would be very appreciated.

Thanks,

H. Dozier