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Radiator Fan System: Inspection

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.
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  . 

Diagnosis: 

Radiator main fan and radiator sub fan do not rotate.

  1. CHECK DTC  .
    1. Turn the ignition switch to ON.
    2. Using the Subaru Select Monitor, read all DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

    Is DTC displayed?

    YES:  Perform the diagnosis for the displayed DTCs.

    NO:  Go to  2.

  2. CHECK RADIATOR MAIN FAN AND RADIATOR SUB FAN OPERATION  .
    1. Using the Subaru Select Monitor, select [Radiator Fan Relay] of [Active Test]. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>ACTIVE TEST .
      NOTE:

      It is also possible to check the operation of the radiator main fan and radiator sub fan with the mode set to the delivery mode and ignition switch to ON. Ref. to  PRE-DELIVERY INSPECTION>PRE-DELIVERY INSPECTION (PDI) PROCEDURE>DELIVERY MODE  . 

    2. Check the operation of the radiator main fan and radiator sub fan.
      NOTE:

      There are following two types of operation patterns of the radiator main fan and radiator sub fan depending on the specifications, and both operations are normal. 

      • Type A 

      "Less than one rotation → stop" is repeated. 

      • Type B 

      "Low speed rotation → stop" is repeated. 

    Do the radiator main fan and radiator sub fan rotate with repetitive ON/OFF operation?

    YES:  Radiator main fan system is normal.

    NO: 

    • When the radiator main fan does not rotate, Go to  3.
    • When the radiator sub fan does not rotate, Go to   12 .  .
  3. CHECK FUSE  .
    1. Turn the ignition switch to OFF.
      NOTE:

      If the delivery mode is set, turn the ignition switch to OFF and then exit the delivery mode. Ref. to  PRE-DELIVERY INSPECTION>PRE-DELIVERY INSPECTION (PDI) PROCEDURE>DELIVERY MODE  . 

    2. Check the SBF-6 and M/B fuse No. 9.

    Is the fuse OK?

    YES:  Go to  4.

    NO:  Replace the fuse.

    NOTE:

    If the fuse is blown again, check the system wiring harness. 

  4. CHECK MAIN FAN RELAY  .
    1. Remove the main fan relay. Ref. to COOLING (H4DOTC)>RADIATOR FAN RELAY>LOCATION .
    2. Perform unit check for the main fan relay. Ref. to COOLING (H4DOTC)>RADIATOR FAN RELAY>INSPECTION .

    Is the main fan relay OK?

    YES:  Go to  5.

    NO:  Replace the main fan relay. Ref. to COOLING (H4DOTC)>RADIATOR FAN RELAY>LOCATION .

  5. CHECK POWER SUPPLY FOR ECM  .
    1. Install the main fan relay. Ref. to COOLING (H4DOTC)>RADIATOR FAN RELAY>LOCATION .
    2. Disconnect the connector from ECM. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>ENGINE CONTROL MODULE (ECM)>REMOVAL .
    3. Turn the ignition switch to ON.
    4. Measure the voltage between ECM connector and chassis ground.

    Connector & terminal 

    (B61) No. 46 (+) - Chassis ground (-):

    Is the voltage 10 V or more?

    YES: Go to   6 .  .

    NO:  Repair the power supply line.

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

    Connector & terminal 

    (Fr31) No. 1 (+) - Chassis ground (-):

    Is the voltage 10 V or more?

    YES: Go to   7 .  .

    NO:  Repair the power supply line.

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

    Connector & terminal 

    (B61) No. 59 - (Fr31) No. 2:

    Is the resistance less than 1 Ω?

    YES:  Go to  8.

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

  8. CHECK GROUND CIRCUIT FOR RADIATOR FAN CONTROL MODULE (MAIN)  .

    Measure the resistance between radiator fan control module (main) connector and chassis ground.

    Connector & terminal 

    (Fr31) No. 3 - Chassis ground:

    Is the resistance less than 5 Ω?

    YES:  Go to  9.

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

  9. CHECK FAN MOTOR (MAIN)  .
    1. Disconnect the fan motor (main) connector.
    2. Apply battery voltage to the fan motor (main) connector.
    NOTE:

    There are two circuit systems of fan motor (main). Therefore, check one system at a time. 

    1. Connect the battery positive terminal to the fan motor (main) connector terminal No. 2.
    2. Connect the battery negative terminal to the fan motor (main) connector terminal No. 1.

    Does the fan motor (main) rotate?

    YES:  Go to  10.

    NO:  Replace the fan motor (main). Ref. to COOLING (H4DOTC)>RADIATOR MAIN FAN AND FAN MOTOR .

  10. CHECK HARNESS BETWEEN RADIATOR FAN CONTROL MODULE (MAIN) AND FAN MOTOR (MAIN)  .
    1. Disconnect the connector from radiator fan control module (main).
    2. Measure the resistance between radiator fan control module (main) connector and fan motor (main) connector.

    Connector & terminal 

    (Fr32) No. 1 - (Fr51) No. 1:

    (Fr32) No. 2 - (Fr51) No. 2:

    Is the resistance less than 1 Ω?

    YES:  Go to  11.

    NO:  Repair the open circuit in harness between radiator fan control module (main) connector and fan motor (main) connector.

  11. CHECK OUTPUT SIGNAL OF ECM  .
    1. Connect the radiator fan control module (main) connector and the fan motor (main) connector.
    2. Turn the ignition switch to ON.
    3. Using the Subaru Select Monitor, select [Radiator Fan Relay] of [Active Test]. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>ACTIVE TEST .
      NOTE:

      It is also possible to check the output signal of ECM with the mode set to the delivery mode and ignition switch to ON. Ref. to  PRE-DELIVERY INSPECTION>PRE-DELIVERY INSPECTION (PDI) PROCEDURE>DELIVERY MODE  . 

    4. Read the output signal waveform using an oscilloscope. Ref. to COOLING (H4DOTC)>RADIATOR FAN SYSTEM>RADIATOR FAN CONTROL OUTPUT WAVEFORM .

    Connector & terminal 

    (B61) No. 59 (+) - Chassis ground (-):

    Does a waveform of the output signal occur?

    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) .

  12. CHECK FUSE  .
    1. Turn the ignition switch to OFF.
      NOTE:

      If the delivery mode is set, turn the ignition switch to OFF and then exit the delivery mode. Ref. to  PRE-DELIVERY INSPECTION>PRE-DELIVERY INSPECTION (PDI) PROCEDURE>DELIVERY MODE  . 

    2. Check the SBF-7 and M/B fuse No. 10.

    Is the fuse OK?

    YES:  Go to  13.

    NO:  Replace the fuse.

    NOTE:

    If the fuse is blown again, check the system wiring harness. 

  13. CHECK SUB FAN RELAY  .
    1. Remove the sub fan relay. Ref. to COOLING (H4DOTC)>RADIATOR FAN RELAY> LOCATION .
    2. Perform unit check for the sub fan relay. Ref. to COOLING (H4DOTC)>RADIATOR FAN RELAY>INSPECTION .

    Is the sub fan relay OK?

    YES:  Go to  14.

    NO:  Replace the sub fan relay. Ref. to COOLING (H4DOTC)>RADIATOR FAN RELAY>LOCATION .

  14. CHECK POWER SUPPLY FOR ECM  .
    1. Install the sub fan relay. Ref. to COOLING (H4DOTC)>RADIATOR FAN RELAY> LOCATION .
    2. Disconnect the connector from ECM. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>ENGINE CONTROL MODULE (ECM)>REMOVAL .
    3. Turn the ignition switch to ON.
    4. Measure the voltage between ECM connector and chassis ground.

    Connector & terminal 

    (B61) No. 45 (+) - Chassis ground (-):

    Is the voltage 10 V or more?

    YES:  Go to  15.

    NO:  Repair the power supply line.

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

    Connector & terminal 

    (Fr33) No. 1 (+) - Chassis ground (-):

    Is the voltage 10 V or more?

    YES:  Go to  16.

    NO:  Repair the power supply line.

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

    Connector & terminal 

    (B61) No. 27 - (Fr33) No. 2:

    Is the resistance less than 1 Ω?

    YES:  Go to  17.

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

  17. CHECK GROUND CIRCUIT FOR RADIATOR FAN CONTROL MODULE (SUB)  .

    Measure the resistance between radiator fan control module (sub) connector and chassis ground.

    Connector & terminal 

    (Fr33) No. 3 - Chassis ground:

    Is the resistance less than 5 Ω?

    YES:  Go to  18.

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

  18. CHECK FAN MOTOR (SUB)  .
    1. Disconnect the fan motor (sub) connector.
    2. Apply battery voltage to the fan motor (sub) connector.
    NOTE:

    There are two circuit systems of fan motor (sub). Therefore, check one system at a time. 

    1. Connect the battery positive terminal to the fan motor (sub) connector terminal No. 2.
    2. Connect the battery negative terminal to the fan motor (sub) connector terminal No. 1.

    Does the fan motor (sub) rotate?

    YES:  Go to  19.

    NO:  Replace the fan motor (sub). Ref. to COOLING (H4DOTC)>RADIATOR SUB FAN AND FAN MOTOR .

  19. CHECK HARNESS BETWEEN RADIATOR FAN CONTROL MODULE (SUB) AND FAN MOTOR (SUB)  .
    1. Disconnect the connector from radiator fan control module (sub).
    2. Measure the resistance between radiator fan control module (sub) connector and fan motor (sub) connector.

    Connector & terminal 

    (Fr34) No. 1 - (Fr52) No. 1:

    (Fr34) No. 2 - (Fr52) No. 2:

    Is the resistance less than 1 Ω?

    YES:  Go to  20.

    NO:  Repair the open circuit in harness between radiator fan control module (sub) connector and fan motor (sub) connector.

  20. CHECK OUTPUT SIGNAL OF ECM  .
    1. Connect the radiator fan control module (sub) connector and the fan motor (sub) connector.
    2. Turn the ignition switch to ON.
    3. Using the Subaru Select Monitor, select [Radiator Fan Relay] of [Active Test]. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>ACTIVE TEST .
      NOTE:

      It is also possible to check the output signal of ECM with the mode set to the delivery mode and ignition switch to ON. Ref. to  PRE-DELIVERY INSPECTION>PRE-DELIVERY INSPECTION (PDI) PROCEDURE>DELIVERY MODE  . 

    4. Read the output signal waveform using an oscilloscope. Ref. to COOLING (H4DOTC)>RADIATOR FAN SYSTEM>RADIATOR FAN CONTROL OUTPUT WAVEFORM .

    Connector & terminal 

    (B61) No. 27 (+) - Chassis ground (-):

    Does a waveform of the output signal occur?

    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) .

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