Joe and Arthur, thanks for the fast response. Since there are only TWO sensors on the thermostat housing, I guess that I can assume that I have the later version, which means that the aux fans are controlled by the 4 wire sensor. Since the thermoswitch is a thermistor, my assumption is that resistance DROPS as coolant termpature rises, correct? If this be the case, then pulling the sensor connector (which would produce infinite resistance across the pins) will NOT trigger the high speed fans as had been previously reported. If this is the case, then I should be able to jumper the two pins for the aux fans, and they should come on, right? I will pull the relay cover this evening and check fuses and also jumper the A/C switch to confirm that part of the circuit and fan integrity. If that proves out the fans (at low speed), can I jumpter the temp sensor pins to confirm high speed fan operation? Please corrrect me if any of my above assumptions are incorrect. Thanks in advance for the help.