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I know All I have is a range of resistance values and corresponding temperature values for the sensor. I need some way to equate the resistance values to volts. Once I have that conversion, I can equate the volts coming from the sensor to temperature values.
Keith, if you have a good meter you can put a +5V reference on one side of the sensor and then heat or cool it to a known temperature and measure the voltage at the othe terminal. Do that for the points of reference you require and you can interpolate the points in between. Basically, you need to reverse engineer the temperature coefficient of the thermistor. Not an easy task, but doable with the right tools.
Also, according to the diagnostics, when the car is completely cold, you can check the accuracy of the coolant and IAT sensors against each other. They should agree within 3 deg. F of each other.