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Home >> Lexus >> 2012 >> IS F V8-5.0L (2UR-GSE) >> Repair and Diagnosis >> Engine, Cooling and Exhaust >> Cooling System >> Radiator Cooling Fan >> Testing and Inspection >> Component Tests and General Diagnostics >> Cooling Fan Circuit

Cooling Fan Circuit





2UR-GSE COOLING: COOLING FAN SYSTEM: Cooling Fan Circuit
- 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 ECUs to regulate the cooling fans. The cooling fan ECUs control each 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 ECUs, achieving both high cooling performance and quietness. The cooling fan speed is determined based on engine coolant temperature, air conditioner operating conditions, engine speed, and vehicle speed.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

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

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Enter the following menus: Powertrain / Engine / Active Test / Control the Electric Cooling Fan.

(d) Check the operation of the cooling fan while operating it using the Techstream.

OK:





Result:





B -- INSPECT COOLING FAN SYSTEM (FOR MAIN FAN)

C -- INSPECT COOLING FAN SYSTEM (FOR SUB FAN)

D -- INSPECT COOLING FAN SYSTEM

A -- REPLACE ECM Removal

2. INSPECT COOLING FAN SYSTEM (FOR MAIN FAN)

(a) Disconnect the cooling fan ECU (for main fan) connector.

(b) Turn the engine switch on (IG).

(c) Check the operation of the cooling fan.

OK:

The cooling fan rotates.

NG -- CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU (FOR MAIN FAN))
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU (FOR MAIN FAN))

(a) Disconnect the cooling fan ECU connector.





(b) Disconnect the ECM connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE COOLING FAN ECU (FOR MAIN FAN)

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

(a) Disconnect the cooling fan ECU connector.





(b) Disconnect the ECM connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

5. INSPECT COOLING FAN MOTOR (FOR MAIN FAN)

(a) Inspect the cooling fan motor Testing and Inspection.

NG -- REPLACE COOLING FAN MOTOR (FOR MAIN FAN) Removal
OK -- Continue to next step.

6. CHECK ECU POWER SOURCE CIRCUIT (FOR MAIN FAN)

(a) Disconnect the cooling fan ECU connector.





(b) Turn the engine switch on (IG).

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

Standard Voltage:





NG -- CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR MAIN FAN) - BODY GROUND)

OK -- REPLACE COOLING FAN ECU (FOR MAIN FAN)

7. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR MAIN FAN) - BODY GROUND)

(a) Disconnect the cooling fan ECU connector.





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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

8. INSPECT FAN NO. 1 RELAY

(a) Remove the FAN No. 1 relay from the engine room No. 1 relay block.





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

Standard Resistance:





NG -- REPLACE FAN NO. 1 RELAY
OK -- Continue to next step.

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

(a) Remove the FAN No. 1 relay from the engine room No. 1 relay block.





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

Standard Voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 1 RELAY - BATTERY)
OK -- Continue to next step.

10. CHECK HARNESS AND CONNECTOR (FAN NO. 1 RELAY - LH-IG FUSE)

(a) Remove the FAN No. 1 relay from the engine room No. 1 relay block.





(b) Turn the engine switch on (IG).

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

Standard Voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

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

(a) Remove the FAN No. 1 relay from the engine room No. 1 relay block.





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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 1 RELAY - BODY GROUND)

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU (FOR MAIN FAN) - FAN NO. 1 RELAY)

12. INSPECT COOLING FAN SYSTEM (FOR SUB FAN)

(a) Disconnect the cooling fan ECU (for sub fan) connector.

(b) Turn the engine switch on (IG).

(c) Check the operation of the cooling fan.

OK:

The cooling fan rotates.

NG -- CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR SUB FAN) - ECM)
OK -- Continue to next step.

13. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR SUB FAN) - ECM)

(a) Disconnect the cooling fan ECU connector.





(b) Disconnect the ECM connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE COOLING FAN ECU (FOR SUB FAN)

14. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR SUB FAN) - ECM)

(a) Disconnect the cooling fan ECU connector.





(b) Disconnect the ECM connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

15. INSPECT NO. 2 COOLING FAN MOTOR (FOR SUB FAN)

(a) Inspect the No. 2 cooling fan motor Testing and Inspection.

NG -- REPLACE NO. 2 COOLING FAN MOTOR (FOR SUB FAN) Removal
OK -- Continue to next step.

16. CHECK ECU POWER SOURCE CIRCUIT (FOR SUB FAN)

(a) Disconnect the cooling fan ECU connector.





(b) Turn the engine switch on (IG).

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

Standard Voltage:





NG -- CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR SUB FAN) - BODY GROUND)

OK -- REPLACE COOLING FAN ECU (FOR SUB FAN)

17. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU (FOR SUB FAN) - BODY GROUND)

(a) Disconnect the cooling fan ECU connector.





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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

18. INSPECT FAN NO. 2 RELAY

(a) Remove the FAN No. 2 relay from the engine room No. 1 relay block.





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

Standard Resistance:





NG -- REPLACE FAN NO. 2 RELAY
OK -- Continue to next step.

19. CHECK HARNESS AND CONNECTOR (FAN NO. 2 RELAY - BATTERY)

(a) Remove the FAN No. 2 relay from the engine room No. 1 relay block.





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

Standard Voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 2 RELAY - BATTERY)
OK -- Continue to next step.

20. CHECK HARNESS AND CONNECTOR (FAN NO. 2 RELAY - LH-IG FUSE)

(a) Remove the FAN No. 2 relay from the engine room No. 1 relay block.





(b) Turn the engine switch on (IG).

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

Standard Voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

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

(a) Remove the FAN No. 2 relay from the engine room No. 1 relay block.





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

Standard Resistance:





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

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU (FOR SUB FAN) - FAN NO. 2 RELAY)

22. INSPECT COOLING FAN SYSTEM

(a) Disconnect the cooling fan ECU (for main and sub fan) connectors.

(b) Turn the engine switch on (IG).

(c) Check the operation of the cooling fan.

OK:

The cooling fan rotates.

NG -- CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU (FOR MAIN AND SUB FAN))
OK -- Continue to next step.

23. CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU (FOR MAIN AND SUB FAN))

(a) Disconnect the cooling fan ECU connector.





(b) Disconnect the ECM connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM Removal

24. CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU (FOR MAIN AND SUB FAN))

(a) Disconnect the cooling fan ECU connector.





(b) Disconnect the ECM connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

25. INSPECT FUSE (LH-IG FUSE)

(a) Remove the LH-IG fuse from the cowl side junction block LH.





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

Standard Resistance:





NG -- REPLACE FUSE (LH-IG FUSE)
OK -- Continue to next step.

26. INSPECT MAIN BODY ECU LH (LH-IG1 RELAY)

(a) Disconnect the main body ECU LH (cowl side junction block LH) connectors.





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

Standard Resistance:





NG -- REPLACE MAIN BODY ECU LH (COWL SIDE JUNCTION BLOCK LH)
OK -- Continue to next step.

27. CHECK HARNESS AND CONNECTOR (LH-IG1 RELAY - FAN NO. 1 RELAY)

(a) Disconnect the main body ECU LH (cowl side junction block LH) connector.









(b) Remove the FAN No. 1 relay from the engine room No. 1 relay block.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

28. CHECK HARNESS AND CONNECTOR (LH-IG1 RELAY POWER SOURCE)

(a) Disconnect the main body ECU (cowl side junction block LH) connector.





(b) Turn the engine switch on (IG).

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

Standard Voltage:





NG -- CHECK HARNESS AND CONNECTOR (MAIN BODY ECU LH - POWER SOURCE CONTROL ECU)
OK -- Continue to next step.

29. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU LH - BODY GROUND)

(a) Disconnect the main body ECU LH (cowl side junction block LH) connector.





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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (MAIN BODY ECU LH - BODY GROUND)

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - MAIN BODY ECU LH)

30. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU LH - POWER SOURCE CONTROL ECU)

(a) Disconnect the main body ECU LH (cowl side junction block LH) connector.





(b) Disconnect the power source control ECU connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START How To Proceed With Troubleshooting
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