I've got this car in with a fault with the air con system but it turns out that the air con won't work as the cooling fan does not operate. It logs code P0691 - Fan1 control circuit low.

The speed controller for the fan motor has 12 volts on it when connected to the speed controller but appears to be open circuit when I disconnect it. This doesn't seem to match the fault code as I'd assume that "circuit low" would mean that the ECU is not seeing any voltage from the speed controller.

I've got little information on this vehicle but I'm guessing its the same as a later Mondeo 2.0 TDCi. Can anyone tell me whether its possible to test the speed controller or can confirm if I should see a voltage from the ECU on the speed controller signal wire when its disconnected from the controller? I've tested the fan and confirmed that it is working ok. I'm guessing that I may have a broken wire or possible ECU fault but just need a bit more info to confirm it!