Mike C.

You are correct Tom, the thermoswitch doesn't 'talk' to the DME. It merely provides a path to ground for the fan to come on when water temp closes the switch. There is a temp sensor on the engine that talks to the DME. I'm sure it works based on resistance change w/temp. What I'm not sure about is if your temperature gage behaves normally does this mean the sensor is O.K.?