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 ECU to regulate the cooling fans. The cooling fan ECU controls the 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 ECU, achieving both high cooling performance and quietness.

WIRING DIAGRAM

A011VC4E01

INSPECTION PROCEDURE

Note

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

PROCEDURE

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

    1. Connect the Techstream to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the Techstream on.

    4. Enter the following menus: Powertrain / Engine / Active Test / Control the Electric Cooling Fan.

    5. Check the operation of the cooling fans while operating them using the Techstream.

      OK
      Techstream Operation Specified Condition
      ON Cooling fans operating
      OFF Cooling fans stopped
      Result
      Result Proceed to
      OK A
      NG (Cooling fans do not operate) B
      NG (Cooling fans do not stop) C
    B

    INSPECT COOLING FAN MOTOR (COOLING FAN MOTOR AND NO. 2 COOLING FAN MOTOR) Click here

    C

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

    A

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

  2. INSPECT COOLING FAN MOTOR (COOLING FAN MOTOR AND NO. 2 COOLING FAN MOTOR)

    1. Inspect the cooling fan motor and No. 2 cooling fan motor Click here.

      Result
      Result Proceed to
      OK A
      NG (Cooling fan motor) B
      NG (No. 2 cooling fan motor) C
    B

    REPLACE COOLING FAN MOTOR Click here

    C

    REPLACE NO. 2 COOLING FAN MOTOR Click here

    A

  3. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU POWER SOURCE)

    1. Disconnect the cooling fan ECU connector.

      A011S3QE02

    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
      A10-3 (+B1) - A10-1 (E1) Engine switch on (IG) 11 to 14 V
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Cooling Fan ECU)
    NG

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

    OK

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

    1. Disconnect the ECM connector.

    2. Disconnect the cooling fan ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A25-5 (RFC) or A10-2 (SI) - Body ground Always 10 kΩ or higher
    NG

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

    OK

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

  5. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU - BODY GROUND)

    1. Disconnect the cooling fan ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A10-1 (E1) - Body ground Always Below 1 Ω
    NG

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

    OK

  6. INSPECT RELAY (FAN RELAY)

    1. Inspect the FAN relay Click here.

    NG

    REPLACE RELAY (FAN RELAY)

    OK

  7. CHECK HARNESS AND CONNECTOR (FAN RELAY POWER SOURCE)

    1. Remove the FAN relay from the engine room relay block and junction block assembly.

      A011S50E02

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      3 (FAN relay) - Body ground Always 11 to 14 V
      Text in Illustration
      *1 Engine Room Relay Block and Junction Block Assembly
      *2 FAN Relay
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN RELAY - BATTERY)

    OK

  8. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU - FAN RELAY)

    1. Remove the FAN relay from the engine room relay block and junction block assembly.

    2. Disconnect the cooling fan ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A10-3 (+B1) - 5 (FAN relay) Always Below 1 Ω
      A10-3 (+B1) or 5 (FAN relay) - Body ground Always 10 kΩ or higher
    NG

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

    OK

  9. CHECK HARNESS AND CONNECTOR (FAN RELAY - BODY GROUND)

    1. Remove the FAN relay from the engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      2 (FAN relay) - Body ground Always Below 1 Ω
    NG

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

    OK

  10. CHECK HARNESS AND CONNECTOR (FAN RELAY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

    1. Remove the FAN relay from the engine room relay block and junction block assembly.

    2. Disconnect the instrument panel junction block assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1 (FAN relay) - 3D-36 Always Below 1 Ω
      1 (FAN relay) or 3D-36 - Body ground Always 10 kΩ or higher
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN RELAY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

    OK

  11. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG1 NO. 2 RELAY)

    1. Disconnect the instrument panel junction block assembly connector.

      A011SCEE02

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3E-1 - 3D-36 Battery voltage is not applied between terminals 3A-27 and 3B-7 10 kΩ or higher
      3E-1 - 3D-36 Battery voltage is applied between terminals 3A-27 and 3B-7 Below 1 Ω
      Text in Illustration
      *1 Instrument Panel Junction Block Assembly
    NG

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG1 NO. 2 RELAY)

    OK

  12. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY POWER SOURCE)

    1. Disconnect the instrument panel junction block assembly connector.

      A011TNME01

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      3E-1 - Body ground Always 11 to 14 V
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Instrument Panel Junction Block Assembly)
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - BATTERY)

    OK

  13. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - BODY GROUND)

    1. Disconnect the instrument panel junction block assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3B-7 - Body ground Always Below 1 Ω
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - BODY GROUND)

    OK

  14. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))

    1. Disconnect the instrument panel junction block assembly connector.

    2. Disconnect the certification ECU (smart key ECU assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3A-27 - I78-6 (IG1D) Always Below 1 Ω
      3A-27 or I78-6 (IG1D) - Body ground Always 10 kΩ or higher
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))

    OK

    CHECK SMART KEY SYSTEM Click here

  15. CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU)

    1. Disconnect the ECM connector.

    2. Disconnect the cooling fan ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A25-5 (RFC) - A10-2 (SI) Always Below 1 Ω
    NG

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

    OK

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