COOLING FAN SYSTEM ON-VEHICLE INSPECTION


  1. INSPECT COOLING FAN SYSTEM


    1. Put the vehicle in the following state:


      1. The ignition switch is off.

      2. The coolant temperature is less than 81°C (178°F).

      3. The battery voltage is between 11 and 14 V.

      4. The A/C switch is off.

    2. Connect the 400 A probe of the ammeter to the M+ terminal of the cooling fan motor.

    3. Turn the ignition switch to the ON position (engine off) and wait for approximately 10 seconds. Check that the fans do not operate.

    4. Start the engine. Check that the fans do not operate with the engine idling.

      Tech Tips

      Make sure that the radiator coolant temperature is less than 81°C (178°F) and the A/C switch is off.

    5. Check that the fans operate when the A/C switch is turned on (The temperature is set to MAX COOL and the magnet clutch is operating).

      Standard current
      No.1 Fan motor
      4 to 23 A
      No.2 Fan motor (w/ air conditioning)
      4 to 23 A

    6. Check that the fans operate when the coolant sensor connector is disconnected.

      Standard current
      No.1 Fan motor
      8 to 23 A
      No.2 Fan motor (w/ air conditioning)
      8 to 23 A

    7. After the engine has warmed up, the fan operates as shown in the illustration.

      A01BGC4E01

      Tech Tips

      The coolant temperature at which the fans start to operate is approximately 77°C (171°F).

      Tech Tips


      • This system can also be checked using the intelligent tester.

      • Select the following menu items: Powertrain / Engine / Data List/ Initial Engine Coolant Temp.

  2. INSPECT COOLING FAN ECU


    1. A01BB91E01

      Check the input voltage.


      1. Disconnect the No. 1 and, if applicable, the No. 2 cooling fan ECU connector.

      2. Turn the ignition switch to the ON position. Measure the voltage at the +B and, if applicable, the +B2 terminal of the disconnected harness side connector.

        Standard voltage
        11 to 14 V

      3. If the terminal voltage is not within the specification, inspect the power source system (fusible link, fuse, wire harness and relay).

    2. Inspect the cooling fan motor.

    3. A01BHZ1E01

      Inspect the wire harness.


      1. Disconnect the ECM and cooling fan ECU connectors.

      2. Measure the resistance between ECM terminal RFC and cooling fan ECU terminal SI and, if applicable, ECM terminal RFC2 and cooling fan ECU terminal SI2.

        Standard resistance
        Below 1 Ω

        Tech Tips

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

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

    4. Inspect the input signal and output current.

      Note

      Be sure to perform the inspection with the radiator coolant temperature less than 75°C (167°F).


      1. A01BA9ME01

        Connect the 400 A probe of the ammeter to the M+ terminal of the cooling fan motor.

      2. Set the intelligent tester to the oscilloscope function.

      3. A01BD5LE03

        Using the intelligent tester, check the waveform between ECM terminals E1 and RFC, and if applicable, E1 and RFC2.

        Standard
        Condition Input signal Output current

        Engine stopped

        IG switch ON

        Wave form 1

        (Duty ratio 0 %)

        		 (Fans do not operate)

        Engine idling

        A/C OFF

        Waveform 1

        (0 %)

        		 (Fans do not operate)

        Engine idling

        A/C ON

        Waveform 2

        (40 to 70 %)

        4 to 23 A

        (Fan operates)
        Engine idling and ECT sensor connector disconnected

        Waveform 3

        (70 %)

        8 to 24 A

        (Fan operates)

        Tech Tips


        • If the input signal is abnormal, there is a malfunction in the ECM or cooling fan ECU.

        • If the output current is abnormal, there is a malfunction in the cooling fan ECU or motor.