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 System Diagram Click here.

INSPECTION PROCEDURE

Note

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

PROCEDURE


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


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG) and turn the tester on.

    3. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Electric Cooling Fan.

    4. Check operation of the cooling fans while operating them using the tester.

      OK
      Tester Operation Fan Operation
      ON Cooling fans operate
      OFF Cooling fans stop
      Result
      Result Proceed to
      OK A
      NG (Main fan) B
      NG (Sub fan) C
      NG (Main and sub fans) D

    B

    INSPECT COOLING FAN SYSTEM (FOR MAIN FAN) Click here

    C

    INSPECT COOLING FAN SYSTEM (FOR SUB FAN) Click here

    D

    INSPECT COOLING FAN SYSTEM (FOR MAIN AND SUB FANS) Click here

    A

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

  2. INSPECT COOLING FAN SYSTEM (FOR MAIN FAN)


    1. Disconnect the A76 ECM connector.

    2. Turn the power switch on (IG).

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

      OK
      The cooling fan (for main fan) operates.

    4. Reconnect the A76 ECM connector.


    NG

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

    OK

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


    1. A01NEMCE01
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Cooling Fan ECU (for Main Fan))
      *2

      Front view of wire harness connector

      (to ECM)

      Disconnect the cooling fan ECU connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A70-2 (SI) - A76-10 (RFC) Always Below 1 Ω

    4. Reconnect the ECM connector.

    5. Reconnect the cooling fan ECU connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE COOLING FAN ECU (FOR MAIN FAN)

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


    1. A01NEMCE01
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Cooling Fan ECU (for Main Fan))
      *2

      Front view of wire harness connector

      (to ECM)

      Disconnect the cooling fan ECU connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A70-2 (SI) or A76-10 (RFC) - Body ground Always 10 kΩ or higher

    4. Reconnect the ECM connector.

    5. Reconnect the cooling fan ECU connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. INSPECT COOLING FAN MOTOR (FOR MAIN FAN)


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


    NG

    REPLACE COOLING FAN MOTOR (FOR MAIN FAN) Click here

    OK

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


    1. A01NGHSE05
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Cooling Fan ECU (for Main Fan))

      Disconnect the cooling fan ECU connector.

    2. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A70-1 (+B1) - A70-3 (E1) Power switch on (IG) 11 to 14 V

    4. Reconnect the cooling fan ECU connector.


    NG

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

    OK

    REPLACE COOLING FAN ECU (FOR MAIN FAN)

  7. CHECK HARNESS OR CONNECTOR (COOLING FAN ECU (FOR MAIN FAN) - BODY GROUND)


    1. Disconnect the cooling fan ECU connector.

    2. A01NGHSE06
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Cooling Fan ECU (for Main Fan))

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A70-3 (E1) - Body ground Always Below 1 Ω

    3. Reconnect the cooling fan ECU connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. INSPECT RELAY (RDI FAN NO. 1)


    1. A01NF9C

      Remove the RDI FAN NO. 1 relay from the engine room relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3 - 5 No battery voltage applied between terminals 1 and 2 10 kΩ or higher
      3 - 5 Battery voltage applied between terminals 1 and 2 Below 1 Ω

    3. Reinstall the RDI FAN NO. 1 relay.


    NG

    REPLACE RELAY (RDI FAN NO. 1)

    OK

  9. CHECK HARNESS AND CONNECTOR (RDI FAN NO. 1 RELAY POWER SOURCE)


    1. A01NH24E02
      Text in Illustration
      *1 Engine Room Relay Block

      Remove the RDI FAN NO. 1 relay from the engine room relay block.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      3 (RDI FAN NO. 1 relay) - Body ground Always 11 to 14 V

    3. Reinstall the RDI FAN NO. 1 relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (RDI FAN NO. 1 RELAY - BATTERY)

    OK

  10. CHECK HARNESS AND CONNECTOR (RDI FAN NO. 1 RELAY POWER SOURCE)


    1. A01NH24E02
      Text in Illustration
      *1 Engine Room Relay Block

      Remove the RDI FAN NO. 1 relay from the engine room relay block.

    2. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      1 (RDI FAN NO. 1 relay) - Body ground Power switch on (IG) 11 to 14 V

    4. Reinstall the RDI FAN NO. 1 relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (RDI FAN NO. 1 RELAY - IG1 RELAY)

    OK

  11. CHECK HARNESS AND CONNECTOR (RDI FAN NO. 1 RELAY - BODY GROUND)


    1. A01NH24E02
      Text in Illustration
      *1 Engine Room Relay Block

      Remove the RDI FAN NO. 1 relay from the engine room relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      2 (RDI FAN NO. 1 relay) - Body ground Always Below 1 Ω

    3. Reinstall the RDI FAN NO. 1 relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU (FOR MAIN FAN) - RDI FAN NO. 1 RELAY)

  12. INSPECT COOLING FAN SYSTEM (FOR SUB FAN)


    1. Disconnect the A76 ECM connector.

    2. Turn the power switch on (IG).

    3. Check operation of the cooling fan (for sub fan).

      OK
      The cooling fan (for sub fan) operates.

    4. Reconnect the A76 ECM connector.


    NG

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

    OK

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


    1. A01NEMCE02
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Cooling Fan ECU (for Sub Fan))
      *2

      Front view of wire harness connector

      (to ECM)

      Disconnect the cooling fan ECU connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A71-2 (SI2) - A76-10 (RFC) Always Below 1 Ω

    4. Reconnect the ECM connector.

    5. Reconnect the cooling fan ECU connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE COOLING FAN ECU (FOR SUB FAN)

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


    1. A01NEMCE02
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Cooling Fan ECU (for Sub Fan))
      *2

      Front view of wire harness connector

      (to ECM)

      Disconnect the cooling fan ECU connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A71-2 (SI2) or A76-10 (RFC) - Body ground Always 10 kΩ or higher

    4. Reconnect the ECM connector.

    5. Reconnect the cooling fan ECU connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  15. INSPECT NO. 2 COOLING FAN MOTOR (FOR SUB FAN)


    1. Inspect the No. 2 cooling fan motor (for sub fan) Click here.


    NG

    REPLACE NO. 2 COOLING FAN MOTOR (FOR SUB FAN) Click here

    OK

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


    1. A01NGHSE07
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Cooling Fan ECU (for Sub Fan))

      Disconnect the cooling fan ECU connector.

    2. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A71-1 (+B2) - A71-3 (E2) Power switch on (IG) 11 to 14 V

    4. Reconnect the cooling fan ECU connector.


    NG

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

    OK

    REPLACE COOLING FAN ECU (FOR SUB FAN)

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


    1. Disconnect the cooling fan ECU connector.

    2. A01NGHSE08
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Cooling Fan ECU (for Sub Fan))

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A71-3 (E2) - Body ground Always Below 1 Ω

    3. Reconnect the cooling fan ECU connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  18. INSPECT RELAY (RDI FAN NO. 2)


    1. A01NF9C

      Remove the RDI FAN NO. 2 relay from the engine room No. 3 relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3 - 5 No battery voltage applied between terminals 1 and 2 10 kΩ or higher
      3 - 5 Battery voltage applied between terminals 1 and 2 Below 1 Ω

    3. Reinstall the RDI FAN NO. 2 relay.


    NG

    REPLACE RELAY (RDI FAN NO. 2)

    OK

  19. CHECK HARNESS AND CONNECTOR (RDI FAN NO. 2 RELAY POWER SOURCE)


    1. A01NHHTE01
      Text in Illustration
      *1 Engine Room No. 3 Relay Block

      Remove the RDI FAN NO. 2 relay from the engine room No. 3 relay block.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      3 (RDI FAN NO. 2 relay) - Body ground Always 11 to 14 V

    3. Reinstall the RDI FAN NO. 2 relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (RDI FAN NO. 2 - BATTERY)

    OK

  20. INSPECT RELAY VOLTAGE (RDI FAN NO. 2 RELAY)


    1. A01NHHTE01
      Text in Illustration
      *1 Engine Room No. 3 Relay Block

      Remove the RDI FAN NO. 2 relay from the engine room No. 3 relay block.

    2. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      1 (RDI FAN NO. 2 relay) - Body ground Power switch on (IG) 11 to 14 V

    4. Reinstall the RDI FAN NO. 2 relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (RDI FAN NO. 2 RELAY - IG1 RELAY)

    OK

  21. CHECK HARNESS AND CONNECTOR (RDI FAN NO. 2 RELAY - BODY GROUND)


    1. A01NHHTE01
      Text in Illustration
      *1 Engine Room No. 3 Relay Block

      Remove the RDI FAN NO. 2 relay from the engine room No. 3 relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      2 (RDI FAN NO. 2 relay) - Body ground Always Below 1 Ω

    3. Reinstall the RDI FAN NO. 2 relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU (FOR SUB FAN) - RDI FAN NO. 2 RELAY)

  22. INSPECT COOLING FAN SYSTEM (FOR MAIN AND SUB FANS)


    1. Disconnect the A76 ECM connector.

    2. Turn the power switch on (IG).

    3. Check operation of the cooling fans (for main and sub fans).

      OK
      The cooling fans (for main and sub fans) operate.

    4. Reconnect the A76 ECM connector.


    NG

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

    OK

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


    1. A01NEMCE03
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Cooling Fan ECU)
      *2

      Front view of wire harness connector

      (to ECM)
      *3 for Main Fan
      *4 for Sub Fan

      Disconnect the cooling fan ECU connectors.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A70-2 (SI) - A76-10 (RFC) Always Below 1 Ω
      A71-2 (SI2) - A76-10 (RFC) Always Below 1 Ω

    4. Reconnect the ECM connector.

    5. Reconnect the cooling fan ECU connectors.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here

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


    1. A01NEMCE03
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Cooling Fan ECU)
      *2

      Front view of wire harness connector

      (to ECM)
      *3 for Main Fan
      *4 for Sub Fan

      Disconnect the cooling fan ECU connectors.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A70-2 (SI) or A76-10 (RFC) - Body ground Always 10 kΩ or higher
      A71-2 (SI2) or A76-10 (RFC) - Body ground Always 10 kΩ or higher

    4. Reconnect the ECM connector.

    5. Reconnect the cooling fan ECU connectors.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  25. CHECK HARNESS AND CONNECTOR (RDI FAN NO. 1 RELAY POWER SOURCE)


    1. A01NH24E02
      Text in Illustration
      *1 Engine Room Relay Block

      Remove the RDI FAN NO. 1 relay from the engine room relay block.

    2. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      1 (RDI FAN NO. 1 relay) - Body ground Power switch on (IG) 11 to 14 V

    4. Reinstall the RDI FAN NO. 1 relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (RDI FAN NO. 1 RELAY - IG1 RELAY)

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (RDI FAN NO. 1 RELAY - BATTERY)