This temp switch switches a ground circuit for the timing and idle control.
Oh forgot here is the test procedure:
-Disconnect the white wire(s) from the switch
-check for continuity between the switch terminal corresponding to the white wire and ground
-at coolant temps below 86 F there should be no continuity
-coolant temps above 118F there should be continuity (switch closed)
Any faults or values out of spec should be addressed by replacing sensor.