SFI SYSTEM


  1. OPERATION


    1. The cooling fan control system achieves an optimal fan speed in accordance with the engine coolant temperature, vehicle speed, engine speed, and air conditioning operating conditions. The ECM calculates the appropriate fan speed and sends signals to the cooling fan ECUs. Upon receiving the signals from the ECM, the cooling fan ECUs actuate the cooling fan motor and No. 2 cooling fan motor.

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    2. As illustrated below, the ECM determines the required cooling fan speed by selecting the fastest fan speed from among the following:


      1. The fan speed required according to the engine coolant temperature (Graph A).

      2. The fan speed required based on the air conditioning refrigerant pressure (Graph B).

      3. The fan speed required by the engine speed (Graph C).

      4. The fan speed required by the vehicle speed (Graph D).

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