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 ECUs to regulate the cooling fans. The cooling fan ECUs control each 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 ECUs, 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.

PROCEDURE


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


    1. Connect the GTS to the DLC3.

    2. Turn the engine 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. Check the operation of the cooling fans while operating them using the GTS.

      OK
      Tester Operation Fan Operation
      ON Cooling fans operate
      OFF Cooling fans stop
      Result
      Result Proceed to
      OK A
      NG (Main fan do not operate) B
      NG (Sub fan do not operate) C
      NG (Main fan do not stop) D
      NG (Sub fan do not stop) E

    6. Turn the engine switch off.


    A

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

    C

    CHECK COOLING FAN SYSTEM (FOR SUB FAN) Click here

    D

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

    E

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

    B

  2. CHECK COOLING FAN SYSTEM (FOR MAIN FAN)


    1. Disconnect the A78 ECM connector.

    2. Turn the engine switch on (IG).

    3. Check the operation of the cooling fan (main fan).

      OK
      The cooling fan (main fan) operates.

    4. Turn the engine switch off.

    5. Reconnect the A78 ECM connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

  3. INSPECT COOLING FAN MOTOR


    1. Inspect the cooling fan motor.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE COOLING FAN MOTOR Click here

    OK

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

    A01VMQ2C07
    *a

    Front view of wire harness connector

    (to Cooling Fan ECU (for Main Fan))

    1. Disconnect the A12 cooling fan ECU (for main fan) connector.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A12-1 (+B1) - A12-3 (E1) Engine switch on (IG) 11 to 14 V

    4. Turn the engine switch off.

    5. Reconnect the A12 cooling fan ECU (for main fan) connector.

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

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


    1. Disconnect the A12 cooling fan ECU (for main fan) connector.

    2. Disconnect the o1 cooling fan ECU (for sub fan) connector.

    3. Disconnect the A78 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A12-2 (SI),o1-2 (SI) or A78-26 (RFC) - Body ground Always 10 kΩ or higher

    5. Reconnect the A78 ECM connector.

    6. Reconnect the o1 cooling fan ECU (for sub fan) connector.

    7. Reconnect the A12 cooling fan ECU (for main fan) connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE COOLING FAN ECU (FOR MAIN FAN)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU (FOR MAIN FAN AND FOR SUB FAN) - ECM)

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


    1. Disconnect the A12 cooling fan ECU (for main fan) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A12-3 (E1) - Body ground Always Below 1 Ω

    3. Reconnect the A12 cooling fan ECU (for main fan) connector.

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  7. INSPECT FAN LH RELAY


    1. Inspect the FAN LH relay.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE FAN LH RELAY

    OK

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


    1. A01VN5HC03
      *1 No. 3 Engine Room Relay Block Assembly
      *2 FAN LH Relay

      Remove the FAN LH relay from the No. 3 engine room relay block assembly.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      1 (FAN LH relay holder) - Body ground Engine switch on (IG) 11 to 14 V
      3 (FAN LH relay holder) - Body ground Always 11 to 14 V

    4. Turn the engine switch off.

    5. Reinstall the FAN LH relay.

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  9. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR MAIN FAN) - FAN LH RELAY)


    1. Disconnect the A12 cooling fan ECU (for main fan) connector.

    2. Remove the FAN LH relay from the No. 3 engine room relay block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A12-1 (+B1) - 5 (FAN LH relay holder) Always Below 1 Ω
      A12-1 (+B1) or 5 (FAN LH relay holder)- Body ground Always 10 kΩ or higher

    4. Reinstall the FAN LH relay.

    5. Reconnect the A12 cooling fan ECU (for main fan) connector.

      Result
      Proceed to
      OK
      NG

    OK

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

    NG

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

  10. CHECK COOLING FAN SYSTEM (FOR SUB FAN)


    1. Disconnect the A78 ECM connector.

    2. Turn the engine switch on (IG).

    3. Check the operation of the cooling fan (main fan).

      OK
      The cooling fan (sub fan) operates.

    4. Turn the engine switch off.

    5. Reconnect the A78 ECM connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

  11. INSPECT NO. 2 COOLING FAN MOTOR


    1. Inspect the No. 2 cooling fan motor.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE NO. 2 COOLING FAN MOTOR Click here

    OK

  12. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR SUB FAN) POWER SOURCE)

    A01VMQ2C18
    *a

    Front view of wire harness connector

    (to Cooling Fan ECU (for Sub Fan))

    1. Disconnect the o1 cooling fan ECU (for sub fan) connector.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      o1-1 (+B) - o1-3 (GND) Engine switch on (IG) 11 to 14 V

    4. Turn the engine switch off.

    5. Reconnect the o1 cooling fan ECU (for sub fan) connector.

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  13. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR MAIN FAN AND FOR SUB FAN) - ECM)


    1. Disconnect the A12 cooling fan ECU (for main fan) connector.

    2. Disconnect the o1 cooling fan ECU (for sub fan) connector.

    3. Disconnect the A78 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A12-2 (SI),o1-2 (SI) or A78-26 (RFC) - Body ground Always 10 kΩ or higher

    5. Reconnect the A78 ECM connector.

    6. Reconnect the o1 cooling fan ECU (for sub fan) connector.

    7. Reconnect the A12 cooling fan ECU (for main fan) connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE COOLING FAN ECU (FOR SUB FAN)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU (FOR MAIN FAN AND FOR SUB FAN) - ECM)

  14. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR SUB FAN) - BODY GROUND)


    1. Disconnect the o1 cooling fan ECU (for sub fan) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      o1-3 (E2) - Body ground Always Below 1 Ω

    3. Reconnect the o1 cooling fan ECU (for sub fan) connector.

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  15. INSPECT FAN RH RELAY


    1. Inspect the FAN RH relay.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE FAN RH RELAY

    OK

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


    1. A01VO48C03
      *1 No. 3 Engine Room Relay Block Assembly
      *2 FAN RH Relay

      Remove the FAN RH relay from the No. 3 engine room relay block assembly.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      1 (FAN RH relay holder) - Body ground Engine switch on (IG) 11 to 14 V
      3 (FAN RH relay holder) - Body ground Always 11 to 14 V

    4. Turn the engine switch off.

    5. Reinstall the FAN RH relay.

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  17. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR SUB FAN) - FAN RH RELAY)


    1. Disconnect the o1 cooling fan ECU (for sub fan) connector.

    2. Remove the FAN RH relay from the No. 3 engine room relay block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      o1-1 (+B) - 5 (FAN RH relay holder) Always Below 1 Ω
      o1-1 (+B) or 5 (FAN RH relay holder)- Body ground Always 10 kΩ or higher

    4. Reinstall the FAN RH relay.

    5. Disconnect the o1 cooling fan ECU (for sub fan) connector.

      Result
      Proceed to
      OK
      NG

    OK

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

    NG

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

  18. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR MAIN FAN) - ECM)


    1. Disconnect the A12 cooling fan ECU (for main fan) connector.

    2. Disconnect the A78 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A12-2 (SI) - A78-26 (RFC) Always Below 1 Ω

    4. Reconnect the A78 ECM connector.

    5. Reconnect the A12 cooling fan ECU (for main fan) connector.

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

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


    1. Disconnect the A cooling fan motor connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A-1 (M-) - Body ground Always 10 kΩ or higher

    3. Reconnect the A cooling fan motor connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE COOLING FAN ECU (FOR MAIN FAN)

    NG

    REPLACE COOLING FAN MOTOR Click here

  20. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR SUB FAN) - ECM)


    1. Disconnect the o1 cooling fan ECU (for sub fan) connector.

    2. Disconnect the A78 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      o1-2 (SI) - A78-26 (RFC) Always Below 1 Ω

    4. Reconnect the A78 ECM connector.

    5. Reconnect the o1 cooling fan ECU (for sub fan) connector.

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

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


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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      B-1 (M-) - Body ground Always 10 kΩ or higher

    3. Reconnect the B No. 2 cooling fan motor connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE COOLING FAN ECU (FOR SUB FAN)

    NG

    REPLACE NO. 2 COOLING FAN MOTOR Click here