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Home >> Lexus >> 2011 >> IS 250C V6-2.5L (4GR-FSE) >> 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





4GR-FSE COOLING: COOLING FAN SYSTEM: Cooling Fan Circuit
- Cooling Fan Circuit

DESCRIPTION

The ECM turns on or off the fan relays using signals calculated from the engine coolant temperature, air conditioning (ON/OFF), air conditioner refrigerant pressure, 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 System Diagram Description and Operation.

INSPECTION PROCEDURE

NOTICE:
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)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

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

(e) Check the operation of the cooling fans while operating them using the Techstream.

OK:





Result:





C -- INSPECT FAN NO. 1 RELAY

B -- CHECK HARNESS AND CONNECTOR (LH-IG1 RELAY - FAN NO. 1, NO. 2 OR NO. 3 RELAY)

A -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures

2. CHECK HARNESS AND CONNECTOR (LH-IG1 RELAY - FAN NO. 1, NO. 2 OR NO. 3 RELAY)

(a) Remove the FAN NO. 1, FAN NO. 2 and FAN NO. 3 relays from the No. 2 engine room relay block.





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

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

Standard Voltage:





Text in Illustration





(d) Reinstall the FAN NO. 1, FAN NO. 2 and FAN NO. 3 relays.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (LH-IG1 RELAY - FAN NO. 1, NO. 2 OR NO. 3 RELAY)
OK -- Continue to next step.

3. INSPECT NO. 2 ENGINE ROOM RELAY BLOCK (FAN NO. 1 OR FAN NO. 3 RELAY VOLTAGE)

(a) Remove the FAN NO. 1 and FAN NO. 3 relays from the No. 2 engine room relay block.





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

Standard Voltage:





Text in Illustration





(c) Reinstall the FAN NO. 1 and FAN NO. 3 relays.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - FAN NO. 1 OR FAN NO. 3 RELAY)
OK -- Continue to next step.

4. INSPECT FAN NO. 1 RELAY

(a) Inspect the FAN NO. 1 relay Testing and Inspection.

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

5. INSPECT FAN NO. 2 RELAY

(a) Inspect the FAN NO. 2 relay Testing and Inspection.

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

6. INSPECT FAN NO. 3 RELAY

(a) Inspect the FAN NO. 3 relay Testing and Inspection.

NG -- REPLACE FAN NO. 3 RELAY
OK -- Continue to next step.

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

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





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

Standard Resistance (Check for Open):





Text in Illustration





(c) Reinstall the FAN NO. 2 relay.

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

8. INSPECT COOLING FAN MOTOR

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

NG -- REPLACE COOLING FAN MOTOR Removal
OK -- Continue to next step.

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

(a) Disconnect the cooling fan motor connector.





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

Standard Resistance (Check for Open):





Text in Illustration





(c) Reconnect the cooling fan motor connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN MOTOR - BODY GROUND)
OK -- Continue to next step.

10. CHECK HARNESS AND CONNECTOR (COOLING FAN MOTOR - FAN NO. 1 OR NO. 2 RELAY)

(a) Disconnect the cooling fan motor connector.





(b) Remove the FAN NO. 1 and FAN NO. 2 relays from the No. 2 engine room relay block.

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

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





Text in Illustration





(d) Reconnect the cooling fan motor connector.

(e) Reinstall the FAN NO. 1 and FAN NO. 2 relays.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN MOTOR - FAN NO. 1 OR NO. 2 RELAY)
OK -- Continue to next step.

11. INSPECT NO. 2 COOLING FAN MOTOR

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

NG -- REPLACE NO. 2 COOLING FAN MOTOR Removal
OK -- Continue to next step.

12. CHECK HARNESS AND CONNECTOR (NO. 2 COOLING FAN MOTOR - FAN NO. 2 OR NO. 3 RELAY)

(a) Disconnect the No. 2 cooling fan motor connector.





(b) Remove the FAN NO. 2 and FAN NO. 3 relays from the No. 2 engine room relay block.

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

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





Text in Illustration





(d) Reconnect the No. 2 cooling fan motor connector.

(e) Reinstall the FAN NO. 2 and FAN NO. 3 relays.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 2 COOLING FAN MOTOR - FAN NO. 2 OR NO. 3 RELAY)
OK -- Continue to next step.

13. INSPECT ENGINE ROOM RELAY BLOCK (FAN NO. 1 RELAY - FAN NO. 2 RELAY)

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





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

Standard Resistance (Check for Open):





Text in Illustration





(c) Reinstall the FAN NO. 1 and FAN NO. 2 relays.

NG -- REPLACE NO. 2 ENGINE ROOM RELAY BLOCK
OK -- Continue to next step.

14. CHECK HARNESS AND CONNECTOR (FAN NO. 2 OR NO. 3 RELAY - ECM)

(a) Remove the FAN NO. 2 and FAN NO. 3 relays from the No. 2 engine room relay block.





(b) Disconnect the ECM connector.

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

Standard Resistance (Check for Open):





Text in Illustration





(d) Reinstall the FAN NO. 2 and FAN NO. 3 relays.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 2 OR NO. 3 RELAY - ECM)

OK -- REPLACE ECM Removal

15. INSPECT FAN NO. 1 RELAY

(a) Inspect the FAN NO. 1 relay Testing and Inspection.

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

16. INSPECT FAN NO. 3 RELAY

(a) Inspect the FAN NO. 3 relay Testing and Inspection.

NG -- REPLACE FAN NO. 3 RELAY
OK -- Continue to next step.

17. CHECK HARNESS AND CONNECTOR (FAN NO. 1, NO. 2 OR NO. 3 RELAY - ECM)

(a) Remove the FAN NO. 1, FAN NO. 2 and FAN NO. 3 relays from the No. 2 engine room relay block.





(b) Disconnect the ECM connector.

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

Standard Resistance (Check for Short):





Text in Illustration





(d) Reinstall the FAN NO. 1, FAN NO. 2 and FAN NO. 3 relays.

(e) Reconnect the ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 1, NO. 2 OR NO. 3 RELAY - ECM)

OK -- REPLACE ECM Removal
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