X3 models have an electric cooling fan placed on the side of the
Radiator, with two types designed for auto- and manual-transmission vehicles. The fan is controlled by the engine control module (ECM) at the output final stage which is located at the side of the fan housing beside the fan motor. It is operated through a pulse width modulated signal and the wiring of the fan circuit is protected by a high amp fuse. Control of the electric fan involves inputs to the ECM such as outlet of the radiator temperature, estimate of the catalytic converter temperature, vehicle speed, battery voltage and estimate of pressure of refrigerant. In the absence of ignition, the electric fan runs at a low rate, which is at 20% then off to establish diagnostics on the vehicle. Since the fan has stored rpm values in the fan output stage, the voltage generated during the decelerating stage of the fan must be appropriate for it to function. In the case that a cooling fan fault is stored in the ECM fault memory, it is advisable to check that the fan is not stuck and can rotate. In case the air conditioning is switched on, the electric fan does not start to rotate immediately, and after the engine stops, the fan may rotate at different speeds for up to 10 min, depending on calculated temperature of the catalyst.