COOLING FAN ECU > ON-VEHICLE INSPECTION

for Preparation Click here



1. CHECK COOLING FAN ECU


A106561E01

  1. Inspect the input voltage.

    1. Disconnect the cooling fan ECU connector.

    2. Turn the engine switch on (IG). Check the voltage of the 3 (+B1) terminal of the wire harness side connector.

      Standard voltage:
      9 to 14 V

      If the result is not as specified, inspect the power source system (fusible link, fuse, wire harness and relay).

  1. Inspect the cooling fan motor (Click here).

  1. Check the resistance of the wire harness side connector between terminals ECM (RFC) and cooling fan ECU (SI).

    1. If the fan does not operate, there may be a short circuit.
    2. If the fan remains operating, there may be an open circuit.

  1. Inspect the ECM power source circuit and ground circuit.



  1. Inspect the input signal and output current.

    HINT:
    Be sure to perform the inspection with the radiator coolant temperature less than 92°C (201°F).




      A110244E01

    1. Connect the 400 A probe of the ammeter to terminals 2 (M+) and 2 (S+) of the cooling fan motor.

    2. Set the intelligent tester to the oscilloscope.



    3. Using the intelligent tester, check the waveform between terminals A10-6 (RFC) and E7-7 (E1) of the ECM.


      H100403E06

      Standard waveform:
      Condition
      		Input Signal
      		Output Current
      Engine stopped
      (Engine switch on (IG))
      		Waveform 1
      (Duty ratio 0 %)
      		(Fan stops)
      Engine idling
      (A/C OFF)
      		Waveform 1
      (0 %)
      		(Fan stops)
      Engine idling
      (A/C ON)
      		Waveform 2
      (40 to 70 %)
      		2 to 11 A
      (Fan operates)
      Engine idling
      (Coolant temperature sensor connector disconnected)
      		Waveform 3
      (60 to 80 %)
      		2 to 11 A
      (Fan operates)

      HINT:
      1. If the input signal is abnormal, there is a malfunction in the ECM or cooling fan ECU.
      2. If the output current is abnormal even when the input signal is normal, there is a malfunction in the cooling fan ECU (RFC) or motor.