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Radiator Fan System: Inspection

WARNING: This page is about a different variant/trim than selected.
CAUTION: Use the check board when measuring the ECM terminal voltage and resistance. Refer to Engine (Diagnostics) (H4DOTC)>General Description>Preparation Tool>How To Use Check Board .

Diagnosis: 

Radiator main fan and radiator sub fan do not rotate.

  1. CHECK DTC  .

    Read the DTC using Subaru Select Monitor. Refer to Common (Diag)>Diagnostic Trouble Code (DTC)>Operation .

    Is DTC detected?

    Yes 

    1. Repair the corresponding system.
    2. Go to  2.

    No  : Go to  2.

  2. CHECK OPERATION OF RADIATOR FAN  .
    1. Turn the ignition switch to OFF.
    2. Using the Subaru Select Monitor, perform the active test for the radiator fan relay. (When using the Subaru Select Monitor) Refer to Engine (Diagnostics) (H4DOTC)>Active Test .
    3. Install the delivery mode fuse, and turn the ignition switch to ON. (When not using the Subaru Select Monitor) Refer to Pre-Delivery Inspection>Pre-Delivery Inspection (PDI) Procedure>Delivery Mode .
    4. Check the radiator main fan operation.

    Does the radiator main fan rotate with repetitive ON/OFF operation?

    Yes  : Go to  3.

    No  : Go to  4.

  3. CHECK OPERATION OF RADIATOR FAN  .
    1. Turn the ignition switch to OFF.
    2. Using the Subaru Select Monitor, perform the active test for the radiator fan relay. (When using the Subaru Select Monitor) Refer to Engine (Diagnostics) (H4DOTC)>Active Test .
    3. Install the delivery mode fuse, and turn the ignition switch to ON. (When not using the Subaru Select Monitor) Refer to Pre-Delivery Inspection>Pre-Delivery Inspection (PDI) Procedure>Delivery Mode .
    4. Check the radiator sub fan operation.

    Does the radiator sub fan rotate with repetitive ON/OFF operation?

    Yes  : Radiator main fan system is normal.

    No  : Go to  13.

  4. CHECK FUSE  .
    1. Turn the ignition switch to OFF.
    2. Check the main fan relay upstream fuse.

    Is the fuse OK?

    Yes  : Go to  5.

    No  : Replace the fuse.

  5. CHECK MAIN FAN RELAY  .
    1. Turn the ignition switch to OFF.
    2. Remove the main fan relay. Refer to COOLING (H4DOTC)>Radiator Fan Relay>LOCATION .
    3. Measure the resistance between terminals on the main fan relay switch side. Refer to COOLING (H4DOTC)>Radiator Fan Relay>INSPECTION .

    Is the resistance 1 MΩ or more?

    Yes  : Go to  6.

    No  : Replace the main fan relay.

  6. CHECK MAIN FAN RELAY  .
    1. Connect the battery to the main fan relay coil side terminal. Refer to COOLING (H4DOTC)>Radiator Fan Relay>INSPECTION .
    2. Measure the resistance between terminals on the main fan relay switch side. Refer to COOLING (H4DOTC)>Radiator Fan Relay>INSPECTION .

    Is the resistance less than 1 Ω?

    Yes  : Go to  7.

    No  : Replace the main fan relay.

  7. CHECK POWER SUPPLY FOR ECM  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Turn the ignition switch to ON.
    4. Measure the voltage between ECM terminal and chassis ground.

    Connector & terminal 

    (B61) No. 12 (+) - Chassis ground (-):

    Is the voltage 10 V or more?

    Yes  : Go to  8.

    No  : Repair the power supply line.

  8. CHECK POWER SUPPLY FOR RADIATOR FAN CONTROL MODULE (MAIN)  .
    1. Turn the ignition switch to OFF.
    2. Connect the connector to ECM.
    3. Disconnect the connector from radiator fan control module (main).
    4. Turn the ignition switch to ON.
    5. Measure the voltage between radiator fan control module (main) terminal and chassis ground.

    Connector & terminal 

    (Fr31) No. 3 (+) - Chassis ground (-):

    Is the voltage 10 V or more?

    Yes  : Go to  9.

    No  : Repair the power supply line.

  9. CHECK HARNESS BETWEEN ECM AND RADIATOR FAN CONTROL MODULE (MAIN)  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Measure the resistance between radiator fan control module (main) and ECM connector.

    Connector & terminal 

    (B61) No. 23 - (Fr31) No. 2:

    Is the resistance less than 1 Ω?

    Yes  : Go to  10.

    No  : Repair the open circuit of harness between ECM and radiator fan control module (main).

  10. CHECK GROUND CIRCUIT FOR RADIATOR FAN CONTROL MODULE (MAIN)  .
    1. Connect the connector to ECM and radiator fan control module (main).
    2. Measure the resistance between radiator fan control module (main) connector and chassis ground.

    Connector & terminal 

    (Fr31) No. 1 - Chassis ground:

    Is the resistance less than 5 Ω?

    Yes  : Go to  11.

    No  : Repair the open circuit of harness between radiator fan control module (main) connector and chassis ground.

  11. CHECK MAIN FAN MOTOR  .
    1. Disconnect the connector from radiator fan control module (main).
    2. Connect the battery positive (+) terminal to terminal No. 2 of the main fan motor, and the ground (-) terminal to terminal No. 1.

    Does the main fan motor rotate?

    Yes  : Go to  12.

    No  : Replace the main fan motor. Refer to COOLING (H4DOTC)>Radiator Fan and Fan Motor Assembly .

  12. CHECK OUTPUT SIGNAL OF ECM  .
    1. Turn the ignition switch to OFF.
    2. Install the delivery mode fuse, and turn the ignition switch to ON. Refer to PRE-DELIVERY INSPECTION>PRE-DELIVERY INSPECTION (PDI) PROCEDURE>DELIVERY MODE .
    3. Check the output waveform using oscilloscope. Refer to COOLING (H4DOTC)>Radiator Fan System>RADIATOR FAN CONTROL OUTPUT WAVEFORM .

    Connector & terminal 

    (B61) No. 23 (+) - Chassis ground (-):

    Is waveform being output?

    Yes  : Replace the radiator fan control module (main). Refer to COOLING (H4DOTC)>Radiator Fan Control Unit .

    No  : Replace the ECM. Refer to Fuel Injection (Fuel Systems) (H4DOTC)>Engine Control Module (ECM) .

    NOTE: After replacing the ECM, check again from step 1.
  13. CHECK FUSE  .
    1. Turn the ignition switch to OFF.
    2. Check the sub fan relay upstream fuse.

    Is the fuse OK?

    Yes  : Go to  14.

    No  : Replace the fuse.

  14. CHECK SUB FAN RELAY  .
    1. Turn the ignition switch to OFF.
    2. Remove the sub fan relay. Refer to COOLING (H4DOTC)>Radiator Fan Relay>LOCATION .
    3. Measure the resistance between sub fan relay switch terminals. Refer to COOLING (H4DOTC)>Radiator Fan Relay>INSPECTION .

    Is the resistance 1 MΩ or more?

    Yes  : Go to  15.

    No  : Replace the sub fan relay.

  15. CHECK SUB FAN RELAY  .
    1. Connect the battery to the terminal on the sub fan relay coil side. Refer to COOLING (H4DOTC)>Radiator Fan Relay>INSPECTION .
    2. Measure the resistance between sub fan relay switch terminals. Refer to COOLING (H4DOTC)>Radiator Fan Relay>INSPECTION .

    Is the resistance less than 1 Ω?

    Yes  : Go to  16.

    No  : Replace the sub fan relay.

  16. CHECK POWER SUPPLY FOR ECM  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Turn the ignition switch to ON.
    4. Measure the voltage between ECM terminal and chassis ground.

    Connector & terminal

    (B61) No. 50 (+) - Chassis ground (-):

    Is the voltage 10 V or more?

    Yes  : Go to  17.

    No  : Repair the power supply line.

  17. CHECK POWER SUPPLY FOR RADIATOR FAN CONTROL MODULE (SUB)  .
    1. Turn the ignition switch to OFF.
    2. Connect the connector to ECM.
    3. Disconnect the connector from radiator fan control module (sub).
    4. Turn the ignition switch to ON.
    5. Measure the voltage between radiator fan control module (sub) terminal and chassis ground.

    Connector & terminal 

    (Fr33) No. 3 (+) - Chassis ground (-):

    Is the voltage 10 V or more?

    Yes  : Go to  18.

    No  : Repair the power supply line.

  18. CHECK HARNESS BETWEEN ECM AND RADIATOR FAN CONTROL MODULE (SUB)  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Measure the resistance between radiator fan control module (sub) and ECM connector.

    Connector & terminal 

    (B61) No. 37 - (Fr33) No. 2:

    Is the resistance less than 1 Ω?

    Yes  : Go to  19.

    No  : Repair the open circuit of harness between ECM and radiator fan control module (sub).

  19. CHECK GROUND CIRCUIT FOR RADIATOR FAN CONTROL MODULE (SUB)  .
    1. Connect the connector to ECM and radiator fan control module (sub).
    2. Measure the resistance between radiator fan control module (sub) connector and chassis ground.

    Connector & terminal 

    (Fr33) No. 1 - Chassis ground:

    Is the resistance less than 5 Ω?

    Yes  : Go to  20.

    No  : Repair the open circuit of harness between radiator fan control module (sub) connector and chassis ground.

  20. CHECK SUB FAN MOTOR  .
    1. Disconnect the connector from radiator fan control module (sub).
    2. Connect the battery positive (+) terminal to terminal No. 2 of the sub fan motor, and the ground (-) terminal to terminal No. 1.

    Does the sub fan motor rotate?

    Yes  : Go to  21.

    No  : Replace the sub fan motor. Refer to COOLING (H4DOTC)>Radiator Fan and Fan Motor Assembly .

  21. CHECK OUTPUT SIGNAL OF ECM  .
    1. Turn the ignition switch to OFF.
    2. Install the delivery mode fuse, and turn the ignition switch to ON. Refer to PRE-DELIVERY INSPECTION>PRE-DELIVERY INSPECTION (PDI) PROCEDURE>DELIVERY MODE .
    3. Check the output waveform using oscilloscope. Refer to COOLING (H4DOTC)>Radiator Fan System>RADIATOR FAN CONTROL OUTPUT WAVEFORM .

    Connector & terminal 

    (B61) No. 37 (+) - Chassis ground (-):

    Is waveform being output?

    Yes  : Replace the radiator fan control module (sub). Refer to COOLING (H4DOTC)>Radiator Fan Control Unit .

    No  : Replace the ECM. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>Engine Control Module (ECM) .

    NOTE: After replacing the ECM, check again from step 1.
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