COOLING FAN SYSTEM Cooling Fan Circuit

DESCRIPTION

The ECM turns on or off the fan relays using signals calculated from the engine coolant temperature, air conditioning switch (on/off) (w/ Air Conditioning System), refrigerant pressure (w/ Air Conditioning System), engine speed and vehicle speed signals.

The ECM switches the circuit of the cooling fan motors between series and parallel by turning on or off the fan relays in order to control the speed of the cooling fan motors in two steps.

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.

  • Before replacing the ECM, refer to Service Bulletin.

PROCEDURE


  1. PERFORM ACTIVE TEST USING GTS


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Active Test / Actuator Test of Fan High Speed


      Powertrain > Engine and ECT > Active Test
      Tester Display
      Actuator Test of Fan High Speed

    5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Actuator Test of Fan Low Speed


      Powertrain > Engine and ECT > Active Test
      Tester Display
      Actuator Test of Fan Low Speed

    6. Perform the Active Test according to the display on the GTS.

      OK
      Tester Operation Fan Operation
      ON (Actuator Test of Fan High Speed) Cooling fans operate in high speed
      ON (Actuator Test of Fan Low Speed) Cooling fans operate in low speed
      OFF Cooling fans stop
      Result
      Proceed to
      OK
      NG

    OK

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

    NG

  2. CHECK HARNESS AND CONNECTOR (FANL - FANH POWER SOURCE)


    1. A01LUYCC01
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A50 ECM connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A50-45 (FANH) - Body ground Ignition switch ON 11 to 14 V
      A50-20 (FANL) - Body ground Ignition switch ON 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT COOLING FAN RELAY (FAN NO. 1, FAN NO. 2 AND FAN NO. 3) Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (FAN NO. 1 RELAY AND FAN NO. 3 RELAY POWER SOURCE CIRCUIT)


    1. A01M243C01
      *1 Engine Room Relay Block and Junction Block Assembly
      *2 FAN NO. 1 relay
      *3 FAN NO. 3 relay

      Remove the FAN NO. 1 relay and FAN NO. 3 relay from the engine room relay block and junction block assembly.

    2. 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 14V
      3 (FAN NO. 3 relay) - Body ground Always 11 to 14V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 1 RELAY AND FAN NO. 3 RELAY POWER SOURCE CIRCUIT)

    OK

  4. INSPECT COOLING FAN RELAY (FAN NO. 1, FAN NO. 2 AND FAN NO. 3)


    1. Inspect the FAN NO. 1 relay, FAN NO. 2 relay and FAN NO. 3 relay.

      Click here

      Result
      Result Proceed to
      OK A
      NG (FAN NO. 1 relay) B
      NG (FAN NO. 2 relay) C
      NG (FAN NO. 3 relay) D

    B

    REPLACE FAN NO. 1 RELAY

    C

    REPLACE FAN NO. 2 RELAY

    D

    REPLACE FAN NO. 3 RELAY

    A

  5. CHECK HARNESS AND CONNECTOR (FAN NO. 2 RELAY - BODY GROUND)


    1. A01LZDLC01
      *1 Engine Room Relay Block and Junction Block Assembly
      *2 FAN NO. 2 relay

      Remove the FAN NO. 2 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 (Check for Open)
      Tester Connection Condition Specified Condition
      5 (FAN NO. 2 relay) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 2 RELAY - BODY GROUND)

    OK

  6. INSPECT COOLING FAN MOTOR


    1. Inspect the cooling fan motor.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE COOLING FAN MOTOR Click here

    OK

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


    1. Disconnect the A112 cooling fan motor connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A112-1 - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  8. CHECK HARNESS AND CONNECTOR (COOLING FAN MOTOR - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY)


    1. Disconnect the A112 cooling fan motor connector.

    2. A01LVUNC01
      *1 Engine Room Relay Block and Junction Block Assembly
      *2 FAN NO. 1 relay
      *3 FAN NO. 2 relay

      Remove the FAN NO. 1 relay and FAN NO. 2 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
      A112-2 - 5 (FAN NO. 1 relay) Always Below 1 Ω
      A112-2 - 4 (FAN NO. 2 relay) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A112-2 or 5 (FAN NO. 1 relay) - Body ground Always 10 kΩ or higher
      A112-2 or 4 (FAN NO. 2 relay) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN MOTOR - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY)

    OK

  9. INSPECT NO. 2 COOLING FAN MOTOR


    1. Inspect the No. 2 cooling fan motor.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE NO. 2 COOLING FAN MOTOR Click here

    OK

  10. CHECK HARNESS AND CONNECTOR (NO. 2 COOLING FAN MOTOR - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY)


    1. Disconnect the A113 No. 2 cooling fan motor connector.

    2. A01M1OAC02
      *1 Engine Room Relay Block and Junction Block Assembly
      *2 FAN NO. 2 relay
      *3 FAN NO. 3 relay

      Remove the FAN NO. 2 relay and FAN NO. 3 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
      A113-1 - 3 (FAN NO. 2 relay) Always Below 1 Ω
      A113-2 - 5 (FAN NO. 3 relay) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A113-1 or 3 (FAN NO. 2 relay) - Body ground Always 10 kΩ or higher
      A113-2 or 5 (FAN NO. 3 relay) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 2 COOLING FAN MOTOR - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY)

    OK

  11. CHECK HARNESS AND CONNECTOR (FAN NO. 1 RELAY - FAN NO. 2 RELAY)


    1. A01LVUNC02
      *1 Engine Room Relay Block and Junction Block Assembly
      *2 FAN NO. 1 relay
      *3 FAN NO. 2 relay

      Remove the FAN NO. 1 relay and FAN NO. 2 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 (Check for Open)
      Tester Connection Condition Specified Condition
      1 (FAN NO. 1 relay) - 1 (FAN NO. 2 relay) Always Below 1 Ω
      2 (FAN NO. 1 relay) - 2 (FAN NO. 2 relay) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      1 (FAN NO. 1 relay) or 1 (FAN NO. 2 relay) - Body ground Always 10 kΩ or higher
      2 (FAN NO. 1 relay) or 2 (FAN NO. 2 relay) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPAIR OR REPLACE ECM Click here

    NG

    REPAIR OR REPLACE ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY

  12. INSPECT COOLING FAN RELAY (FAN NO. 1, FAN NO. 2 AND FAN NO. 3)


    1. Inspect the FAN NO. 1 relay, FAN NO. 2 relay and FAN NO. 3 relay.

      Click here

      Result
      Result Proceed to
      OK A
      NG (FAN NO. 1 relay) B
      NG (FAN NO. 2 relay) C
      NG (FAN NO. 3 relay) D

    B

    REPLACE FAN NO. 1 RELAY

    C

    REPLACE FAN NO. 2 RELAY

    D

    REPLACE FAN NO. 3 RELAY

    A

  13. CHECK HARNESS AND CONNECTOR (ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY - ECM)


    1. A01LY6SC01
      *1 Engine Room Relay Block and Junction Block Assembly
      *2 FAN NO. 1 relay
      *3 FAN NO. 2 relay
      *4 FAN NO. 3 relay

      Remove the FAN NO. 1 relay, FAN NO. 2 relay and FAN NO. 3 relay from the engine room relay block and junction block assembly.

    2. Disconnect the A50 ECM connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      2 (FAN NO. 1 relay) - A50-45 (FANH) Always Below 1 Ω
      2 (FAN NO. 2 relay) - A50-45 (FANH) Always Below 1 Ω
      2 (FAN NO. 3 relay) - A50-20 (FANL) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      2 (FAN NO. 1 relay) or A50-45 (FANH) - Body ground Always 10 kΩ or higher
      2 (FAN NO. 2 relay) or A50-45 (FANH) - Body ground Always 10 kΩ or higher
      2 (FAN NO. 3 relay) or A50-20 (FANL) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY- ECM)