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Radiator Fan System: Inspection

CAUTION: Use the check board when measuring the ECM terminal voltage and resistance. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>General Description>PREPARATION TOOL>HOW TO USE CHECK BOARD .

Operating condition: 

Radiator fan operates depending on the radiator fan speed related to engine coolant temperature or the radiator fan speed related to A/C compressor load, whichever is higher as a load condition.

G13862890Courtesy of SUBARU OF AMERICA, INC.

Diagnosis: 

Radiator main fan and radiator sub fan do not rotate under the above operating conditions.

  1. CHECK DTC  .

    Read the DTC using Subaru Select Monitor. Ref. 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) Ref. 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) Ref. 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) Ref. 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) Ref. 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. Ref. to COOLING (H4DOTC)>Radiator Fan Relay>LOCATION .
    3. Measure the resistance between terminals on the main fan relay switch side. Ref. 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. Ref. to COOLING (H4DOTC)>Radiator Fan Relay>INSPECTION .
    2. Measure the resistance between terminals on the main fan relay switch side. Ref. 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 

    (B134) 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 

    (F106) No. 1 (+) - 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 

    (B134) No. 23 - (F106) 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 

    (F106) No. 3 - 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. 1 of the main fan motor, and the ground (-) terminal to terminal No. 2.

    Does the main fan motor rotate?

    Yes 

    Go to  12.

    No 

    Replace the main fan motor. Ref. 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. Ref. to PRE-DELIVERY INSPECTION>PRE-DELIVERY INSPECTION (PDI) PROCEDURE>DELIVERY MODE .
    3. Check the output waveform using oscilloscope. Ref. to COOLING (H4DOTC)>Radiator Fan System>RADIATOR FAN CONTROL OUTPUT WAVEFORM .

    Connector & terminal 

    (B134) No. 23 (+) - Chassis ground (-):

    Is waveform being output?

    Yes 

    Replace the radiator fan control module (main). Ref. to COOLING (H4DOTC)>RADIATOR FAN CONTROL UNIT .

    No 

    Replace the ECM. Ref. 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. Ref. to COOLING (H4DOTC)>Radiator Fan Relay>LOCATION .
    3. Measure the resistance between sub fan relay switch terminals. Ref. 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. Ref. to COOLING (H4DOTC)>Radiator Fan Relay>INSPECTION .
    2. Measure the resistance between sub fan relay switch terminals. Ref. 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 

    (B134) 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 

    (F22) No. 1 (+) - 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 

    (B134) No. 37 - (F22) 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 

    (F22) No. 3 - 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. 1 of the sub fan motor, and the ground (-) terminal to terminal No. 2.

    Does the sub fan motor rotate?

    Yes 

    Go to  21.

    No 

    Replace the sub fan motor. Ref. 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. Ref. to PRE-DELIVERY INSPECTION>PRE-DELIVERY INSPECTION (PDI) PROCEDURE>DELIVERY MODE .
  3. Check the output waveform using oscilloscope. Ref. to COOLING (H4DOTC)>Radiator Fan System>RADIATOR FAN CONTROL OUTPUT WAVEFORM .

Connector & terminal 

(B134) No. 37 (+) - Chassis ground (-):

Is waveform being output?

Yes 

Replace the radiator fan control module (sub). Ref. to COOLING (H4DOTC)>RADIATOR FAN CONTROL UNIT .

No 

Replace the ECM. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>ENGINE CONTROL MODULE (ECM) .

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