I've seen a couple of guides about making a manual cooling fan override switch and I thought I'd throw this idea out there which relates to all Duratec cars I believe How I understand the system works (UPDATED): The 'submarine' mounted temperature sender feeds the dashboard gauge, there is a separate sensor that sends a reading to the ECU. The ECU then controls the fan circuit when the temperature reading is above the switch point (correct?) Instead of creating a whole new circuit that directly controls the fan power would it be feasible to simply fit a switch that disconnects the ECU wire from the temperature sender? This would send a 'max' value to the ECU and it would then start the cooling fan? (UPDATE - I just plugged in Easimap and pulled the plug off the sender and the coolant temperature reading went to 110 degC so I am guessing this would permanently operate the fan until reconnected). As far as I can see - fitting a switch that simulates unplugging the sender would work without any issues, please feel free to point out if I have any (more) of this wrong, it is something I may look at doing as a precaution in case the sender fails on a blat. Thanks, O.