Hello again.
That is your coolant temperature sensor. Having this not working properly if the harness/connection being bad and not having a thermostat installed will throw your trucks computer into chaos. Not having a thermostat installed will not let the coolant sit in the radiator to stay inside long enough to heat in the winter, or cool in the summer. I've attached a picture below of what a coolant temp sensor is from AutoZone. Can't tell from your picture if the wiring harness broke or the sensor plug connection broke. To hard to tell from the picture. Hope this helps and thanks again for using 2CarPros.
Danny-
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Tuesday, December 17th, 2019 AT 5:09 AM