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 signals to the cooling fan ECU to regulate the cooling fan. 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

Refer to the System Diagram.

Click here

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


  1. PERFORM ACTIVE TEST USING GTS (Control the Electric Cooling Fan)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

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


      Powertrain > Engine and ECT > Active Test
      Tester Display
      Control the Electric Cooling Fan

    5. Check the operation of the cooling fan while operating it using the GTS.

      OK
      Tester Operation Fan Operation
      ON Cooling fan operates
      OFF Cooling fan stops
      Result
      Result Proceed to
      OK A
      Cooling fan does not operate B
      Cooling fan does not stop C

    A

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

    C

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

    B

  2. INSPECT COOLING FAN MOTOR


    1. Inspect the cooling fan motor.

      Click here

      Result
      Result
      OK
      NG

    NG

    REPLACE COOLING FAN MOTOR Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)


    1. Disconnect the A41 cooling fan ECU connector.

    2. Turn the ignition switch to ON.

    3. A01M1HXC04
      *a

      Front view of wire harness connector

      (to Cooling Fan ECU)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A41-1(+B1) - A41-3(E1) Ignition switch ON 11 to 14 V

    4. Reconnect the A41 cooling fan ECU connector.

      Result
      Result
      OK
      NG

    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 A101 ECM connector.

    2. Disconnect the A41 cooling fan ECU connector.

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

      Standard Resistance (Check for Short)
      w/o Glow Plug Controller
      Tester Connection Condition Specified Condition
      A101-19(RFC) or A41-2(SI) - Body ground Always 10 kΩ or higher
      w/ Glow Plug Controller
      Tester Connection Condition Specified Condition
      A169-7(RFC) or A41-2(SI) - Body ground Always 10 kΩ or higher

    4. Reconnect the A41 cooling fan ECU connector.

    5. Reconnect the A101 ECM connector.

      Result
      Result
      OK
      NG

    OK

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

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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


    1. Disconnect the A41 cooling fan ECU connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A41-3(E1) - Body ground Always Below 1 Ω

    3. Reconnect the A41 cooling fan ECU connector.

      Result
      Result
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. INSPECT FAN NO. 1 RELAY


    1. Inspect the FAN NO. 1 relay.

      Click here

      Result
      Result
      OK
      NG

    NG

    REPLACE FAN NO. 1 RELAY

    OK

  7. INSPECT ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY (FAN NO. 1 RELAY)


    1. Remove the FAN NO. 1 relay from the engine room relay block and junction block assembly.

    2. A01LVUYC03
      *1 Engine Room Relay Block and Junction Block Assembly
      *2 FAN NO. 1 Relay

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

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

    3. Reinstall the FAN NO. 1 relay.

      Result
      Result
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU - FAN NO. 1 RELAY)


    1. Disconnect the A41 cooling fan ECU connector.

    2. Remove the FAN NO. 1 relay from the engine room relay block and junction block assembly.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A41-1(+B1) - 5 (FAN NO. 1 relay) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A41-1 (+B1) or 5 (FAN NO. 1 relay) - Body ground Always 10 kΩ or higher

    4. Reinstall the FAN NO. 1 relay.

    5. Reconnect the A41 cooling fan ECU connector.

      Result
      Result
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Remove the FAN NO. 1 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 NO. 1 relay) - Body ground Always Below 1 Ω

    3. Reinstall the FAN NO. 1 relay.

      Result
      Result
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. CHECK HARNESS AND CONNECTOR (FAN NO. 1 RELAY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)


    1. Remove the FAN NO. 1 relay from the engine room relay block and junction block assembly.

    2. Disconnect the 3A instrument panel junction block assembly connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      1 (FAN NO. 1 relay) - 3A-37 Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      1 (FAN NO. 1 relay) or 3A-37 - Body ground Always 10 kΩ or higher

    4. Reconnect the 3A instrument panel junction block assembly connector.

    5. Reinstall the FAN NO. 1 relay.

      Result
      Result
      OK
      NG

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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


    1. Disconnect the A101 ECM connector.

    2. Disconnect the A41 cooling fan ECU connector.

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

      Standard Resistance (Check for Open)
      w/o Glow Plug Controller
      Tester Connection Condition Specified Condition
      A101-19(RFC) - A41-2(SI) Always Below 1 Ω
      w/ Glow Plug Controller
      Tester Connection Condition Specified Condition
      A169-7(RFC) or A41-2(SI) Always Below 1 Ω

    4. Reconnect the A41 cooling fan ECU connector.

    5. Reconnect the A101 ECM connector.

      Result
      Result
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  12. CHECK HARNESS AND CONNECTOR (COOLING FAN MOTOR - BODY GROUND)


    1. Disconnect the z5 cooling fan motor connector.

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

      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      z5-1(-) - Body ground Always 10 kΩ or higher

    3. Reconnect the z5 cooling fan motor connector.

      Result
      Result
      OK
      NG

    OK

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

    NG

    REPLACE COOLING FAN MOTOR Click here