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

Refer to the System Diagram.

Click here

CAUTION / NOTICE / HINT

PROCEDURE

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

   
   

   1. Connect the GTS to the DLC3.

   2. Turn the engine switch on (IG).

   3. Turn the GTS on.

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

      
      Powertrain > Engine > Active Test

      Tester Display
      Control the Electric Cooling Fan

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

      OK
      Tester Operation Fan Operation ON Cooling fans operate OFF Cooling fans stop

      Result
      Result Proceed to OK A NG (Cooling fans do not operate) B NG (Cooling fans do not stop) C

   6. Turn the engine switch off.

   
   

   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. CHECK COOLING FAN SYSTEM

   
   
   1. 

      *a	Rear view of wire harness connector (to ECM)

      Disconnect the A70 ECM connector.

   2. Turn the engine switch on (IG).

   3. Check the operation of the cooling fans.

      OK
      Cooling fans operate.

   4. Turn the engine switch off.

   5. Reconnect the A70 ECM connector.

      Result
      Result OK NG

   
   

   OK

   REPLACE ECM Click here

   NG

3. 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

4. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

   
   

   1. Disconnect the A38 cooling fan ECU connector.

   2. Turn the engine switch on (IG).

   3. 

      *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 A38-3(+B1) - A38-1(E1) Engine switch on (IG) 11 to 14 V

   4. Reconnect the A38 cooling fan ECU connector.

      Result
      Proceed to OK NG

   
   

   NG

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

   OK

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

   
   

   1. Disconnect the A70 ECM connector.

   2. Disconnect the A38 cooling fan ECU connector.

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

      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition A70-19(RFC) or A38-2(SI) - Body ground Always 10 kΩ or higher

   4. Reconnect the A38 cooling fan ECU connector.

   5. Reconnect the A70 ECM connector.

      Result
      Proceed to OK NG

   
   

   OK

   REPLACE COOLING FAN ECU

   NG

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

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

   
   

   1. Disconnect the A38 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 A38-1(E1) - Body ground Always Below 1 Ω

   3. Reconnect the A38 cooling fan ECU connector.

      Result
      Proceed to OK NG

   
   

   NG

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

   OK

7. INSPECT FAN RELAY

   
   

   1. Inspect the FAN relay.

      Click here

      Result
      Proceed to OK NG

   
   

   NG

   REPLACE FAN RELAY

   OK

8. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

   
   
   1. 

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

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

   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 1 (FAN relay holder) - Body ground Engine switch on (IG) 11 to 14 V 3 (FAN relay holder) - Body ground Always 11 to 14 V

   4. Turn the engine switch off.

   5. Reinstall the FAN relay.

      Result
      Proceed to OK NG

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

   OK

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

   
   

   1. Disconnect the A38 cooling fan ECU connector.

   2. Remove the FAN relay from the No. 2 engine room relay block and No. 2 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 A38-3(+B1) - 5 (FAN relay holder) Always Below 1 Ω

      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition A38-3 (+B1) or 5 (FAN relay holder) - Body ground Always 10 kΩ or higher

   4. Reinstall the FAN relay.

   5. Reconnect the A38 cooling fan ECU connector.

      Result
      Result OK NG

   
   

   OK

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

   NG

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

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

    
    

    1. Disconnect the A70 ECM connector.

    2. Disconnect the A38 cooling fan ECU connector.

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

       Standard Resistance (Check for Open)
       Tester Connection Condition Specified Condition A70-19(RFC) - A38-2(SI) Always Below 1 Ω

    4. Reconnect the A38 cooling fan ECU connector.

    5. Reconnect the A70 ECM connector.

       Result
       Proceed to OK NG

    
    

    NG

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

    OK

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

    
    

    1. Disconnect the z10 cooling fan motor connector.

    2. 

       *a	Component without harness connected (Cooling fan motor)

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

       Standard Resistance (Check for Short)
       Tester Connection Condition Specified Condition z10-1 (M-) - Body ground Always 10 kΩ or higher

    3. Reconnect the z10 cooling fan motor connector.

       Result
       Proceed to OK NG

    
    

    NG

    REPLACE COOLING FAN MOTOR Click here

    OK

12. CHECK HARNESS AND CONNECTOR (NO. 2 COOLING FAN MOTOR - BODY GROUND)

    
    

    1. Disconnect the z9 No. 2 cooling fan motor connector.

    2. 

       *a	Component without harness connected (No. 2 cooling fan motor)

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

       Standard Resistance (Check for Short)
       Tester Connection Condition Specified Condition z9-1 (M-) - Body ground Always 10 kΩ or higher

    3. Reconnect the z9 No. 2 cooling fan motor connector.

       Result
       Proceed to OK NG

    
    

    OK

    REPLACE COOLING FAN ECU

    NG

    REPLACE NO. 2 COOLING FAN MOTOR Click here