On Properly Setting Your Cooling Fan Temperature Threshold
When I first installed an aftermarket ECU (Megasquirt I) in my 1984 300ZX, years ago (almost 10 as of this writing!), I used the recommended GM sensor for coolant temperature. It required a bit of machining to fit the sensor, nothing major.
With my latest engine (and the two cars it was in), I decided to use the OEM Cylinder Head Temperature Sensor, since hey, why not? It was already there, in an optimal spot. All I had to do was make software changes to calibrate MS-II to it’s temperature/resistance curve. I had the data in the Factory Service Manual, all was well.