COOLING FAN SYSTEM Cooling Fan Circuit

DESCRIPTION

The ECM calculates an appropriate cooling fan speed based on the engine coolant temperature, air conditioning switch condition, refrigerant pressure, engine speed and vehicle speed, and sends the signals to the cooling fan ECU to regulate the cooling fans. The cooling fan ECU controls the cooling fan speed based on the duty ratio signal sent from the ECM. By basing its control on the operating conditions, the ECM can control the fan speed optimally using the cooling fan ECU, achieving both high cooling performance and quietness.

WIRING DIAGRAM

Refer to the System Diagram.

Click here

CAUTION / NOTICE / HINT

Note


  • Inspect the fuses for circuits related to this system before performing the following procedure.

  • Before replacing the ECM, refer to Service Bulletin.

PROCEDURE


  1. PERFORM ACTIVE TEST USING GTS (CONTROL THE ELECTRIC COOLING FAN)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine / Active Test / Control the Electric Cooling fan.


      Powertrain > Engine > Active Test
      Tester Display
      Control the Electric Cooling Fan

    5. Perform the Active Test according to the display on the GTS.

      OK
      Active Test Operation Fan Operation
      ON Cooling fans operate
      OFF Cooling fans stop
      Result
      Result Proceed to
      OK A
      NG (Cooling fans do not operate) B
      NG (Cooling fans do not stop) C

    A

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    C

    CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU) Click here

    B

  2. CHECK COOLING FAN SYSTEM


    1. Disconnect the A72 ECM connector.

    2. Turn the power switch on (IG).

    3. Check the operation of the cooling fans.

      OK
      Cooling fans operate.
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

  3. INSPECT COOLING FAN MOTOR (COOLING FAN MOTOR AND NO. 2 COOLING FAN MOTOR)


    1. Inspect the cooling fan motor and No. 2 cooling fan motor.

      Click here

      Result
      Result Proceed to
      OK A
      NG (Cooling fan motor) B
      NG (No. 2 Cooling fan motor) C

    B

    REPLACE COOLING FAN MOTOR Click here

    C

    REPLACE NO. 2 COOLING FAN MOTOR Click here

    A

  4. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU POWER SOURCE CIRCUIT)


    1. Disconnect the A38 cooling fan ECU connector.

    2. Turn the power switch on (IG).

    3. A01OCH8C35
      *a

      Front view of wire harness connector

      (to Cooling Fan ECU)

      Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A38-3 (+B1) - A38-1 (E1) Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (COOLING FAN ECU - BODY GROUND) Click here

    OK

  5. CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU)


    1. Disconnect the A72 ECM connector.

    2. Disconnect the A38 cooling fan ECU connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A72-44 (RFC) or A38-2 (SI) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE COOLING FAN ECU

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - COOLING FAN ECU)

  6. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU - BODY GROUND)


    1. Disconnect the A38 cooling fan ECU connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A38-1 (E1) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU - BODY GROUND)

    OK

  7. INSPECT FAN RELAY


    1. Inspect the FAN relay.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE FAN RELAY

    OK

  8. CHECK HARNESS AND CONNECTOR (FAN RELAY POWER SOURCE CIRCUIT)


    1. Remove the FAN relay from the No. 1 engine room relay block and No. 1 junction block assembly.

    2. A01OAI5C01
      *1 No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
      *2 FAN Relay

      Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      3 (FAN relay) - Body ground Power switch off 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN RELAY POWER SOURCE CIRCUIT)

    OK

  9. CHECK HARNESS AND CONNECTOR (FAN RELAY POWER SOURCE CIRCUIT)


    1. Remove the FAN relay from the No. 1 engine room relay block and No. 1 junction block assembly.

    2. Turn the power switch on (IG).

    3. A01OAI5C01
      *1 No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
      *2 FAN Relay

      Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      1 (FAN relay) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT SEMICONDUCTOR PWR INTEGRATION ECU Click here

    OK

  10. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU - FAN RELAY)


    1. Disconnect the A38 cooling fan ECU connector.

    2. Remove the FAN relay from the No. 1 engine room relay block and No. 1 junction block assembly.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A38-3(+B1) - 5 (FAN relay) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A38-3 (+B1) or 5 (FAN relay) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN RELAY - BODY GROUND)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU - FAN RELAY)

  11. INSPECT SEMICONDUCTOR PWR INTEGRATION ECU


    1. Inspect the semiconductor pwr integration ECU.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE SEMICONDUCTOR PWR INTEGRATION ECU Click here

    OK

  12. CHECK HARNESS AND CONNECTOR (FAN RELAY - SEMICONDUCTOR PWR INTEGRATION ECU)


    1. Remove the FAN relay from the No. 1 engine room relay block and No. 1 junction block assembly.

    2. Remove the semiconductor pwr integration ECU from the No. 1 engine room relay block and No. 1 junction block assembly.

      Click here

    3. Disconnect the 1G semiconductor pwr integration ECU connector.

    4. A01OAI5C01
      *1 No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
      *2 FAN Relay

      Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      1 (FAN relay) - 1G-1 Power switch off Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      1 (FAN relay) or 1G-1 - Body ground Power switch off 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN RELAY - SEMICONDUCTOR PWR INTEGRATION ECU)

    OK

  13. CHECK HARNESS AND CONNECTOR (ECM - SEMICONDUCTOR PWR INTEGRATION ECU)


    1. Disconnect the A72 ECM connector.

    2. Remove the semiconductor pwr integration ECU from the No. 1 engine room relay block and No. 1 junction block assembly.

      Click here

    3. Disconnect the 1G semiconductor pwr integration ECU connector.

    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A72-46 (MREL) - 1G-6 Power switch off Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A72-46 (MREL) - 1G-6 - Body ground Power switch off 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - SEMICONDUCTOR PWR INTEGRATION ECU)

  14. CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU)


    1. Disconnect the A72 ECM connector.

    2. Disconnect the A38 cooling fan ECU connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A72-44 (RFC) - A38-2 (SI) Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - COOLING FAN ECU)

    OK

  15. CHECK HARNESS AND CONNECTOR (COOLING FAN MOTOR - BODY GROUND)


    1. Disconnect the z10 cooling fan motor connector.

    2. A01OD83C48
      *a

      Component without harness connected

      (Cooling Fan Motor)

      Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      z10-1 (M-) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE COOLING FAN MOTOR Click here

    OK

  16. CHECK HARNESS AND CONNECTOR (NO. 2 COOLING FAN MOTOR - BODY GROUND)


    1. Disconnect the z9 No. 2 cooling fan motor connector.

    2. A01OALOC04
      *a

      Component without harness connected

      (No. 2 Cooling Fan Motor)

      Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      z9-1 (M-) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE COOLING FAN ECU

    NG

    REPLACE NO. 2 COOLING FAN MOTOR Click here