OK so I just bought a 95 F250 with the 7.3 and the coolant temp gauge is not working. Tried replacing the coolant sensor and nothing. I got 3.6 volts at the connector to the sensor, it seems too low to me what should the voltage be at?

 

You have a short or the wiring is just old and bad. It needs to be closer to 10. You might need to replace it. My 96 had the same issue but as long as the coolant stays full and you replace the crappy ford cap with a good $5 one from a parts house you should be fine