[rotorwrench]

A little history on your pickup might help us. Do you know if the dash speedo/gauge unit was ever worked on or restored? Do you know if the temp gauge ever worked normally during your ownership of the vehicle?

Most all of the Ford/King Seeley engine coolant temp gauges worked the same way in that early 8BA era. If it is reading H or Hot when no power is applied then that is as it should be. If it goes cold when power is applied to a functional circuit with senders connected properly then that is as it should be. If it reads cold power off, then it is likely a gauge from a different system or some sort of repro set up from the modern era.