Okay, here's my experience with my 95 accord. The front sensor/switch (in the water outlet housing) controls the radiator fan when the car is off. It appears to be an on/off switch. It is 2 wire and when jumpered turns the fan on when the car is off. When the car is on and the wires are jumpered it does nothing. The rear sensor/switch (in the thermostat housing) turns the fans on when the switch gets hot enough and closes. It is 2 wire. When jumpered and the car is on, both fans turn on. It does nothing when the car is off. Both of these sensors/switches are in a circuit with the fan relay, fuse, and fan timer module (behind the glove box).