I haven't yet replaced the parts, but a few more observations.
If the cooling system control turns off the fans at a temperature that is lower than where the thermostat closes, then the fans will never turn off. This is because once the thermostat closes with the fans on the temperature at the sensor will stop decreasing and the shutoff temperature will never be reached.
So, there are three possible causes: (1) Sensor reads higher than the actual temperature [can be due to sensor or the circuit] (2) Thermostat closes at too high a temperature (3) The engine control computer is getting the correct temperature but does not command the fan to turn off until a lower temperature than the thermostat closes.
Known:
-The thermostat for this engine should open at 190 degF.
-The temperature reading from the sensor (which is located in close proximity to the thermostat) is greater than ~196 degF.
-The thermostat is closed at this temperature
-The outlet temperature is much lower than the scan tool reports
-The temperature gauge seems to roughly agree with the computer sensor.
-The sensor temperature is correct for room temperature.
Together, these seem to point to the thermostat closing at a higher temperature than it should. A conclusive check would be to monitor the temperature with the thermocouple next to the temperature sensor.