Simple "Waterproof Cooling Fan" for parts diagnosis is not feasible, taking into account the occasional failure, combined with the maintenance of the case before, according to the control strategy of the cooling fan control system, if there is a cooling fan after the flame often turn, must meet "Waterproof Cooling Fan"control unit without the engine control unit duty cycle control signal, the cooling fan control unit of an electric power supply terminal to have. If the "Waterproof Cooling Fan" control unit has been powered electric fuse SC44 must often and J271 should pull. Fault diagnosis based on the detection of J271 after pulling the cooling fan stops rotating case, you can determine the fuse SC44 back line is not shorted, the causes of the fan rotation is always pull J271 cause.