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Home >> Toyota >> 2012 >> Prius L4-1.8L (2ZR-FXE) Hybrid >> 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





2ZR-FXE 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 switch (on/off), air conditioning 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 power switch on (IG).

(c) Turn the Techstream on.

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

OK:





NG -- INSPECT ECM (FANL AND FANH VOLTAGE)

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

2. INSPECT ECM (FANL AND FANH VOLTAGE)

(a) Disconnect the ECM connector.





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

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

Standard Voltage:





Text in Illustration





(d) Reconnect the ECM connector.

NG -- CHECK FUSE (ECU-IG NO. 1 FUSE VOLTAGE)
OK -- Continue to next step.

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

(a) Remove the FAN No. 1 relay and FAN No. 3 relay from the 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 relay and FAN No. 3 relay.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - ENGINE ROOM RELAY BLOCK)
OK -- Continue to next step.

4. INSPECT FAN NO. 1 RELAY

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





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

Standard Resistance:





(c) Reinstall the FAN No. 1 relay.

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

5. INSPECT FAN NO. 2 RELAY

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





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

Standard Resistance:





(c) Reinstall the FAN No. 2 relay.

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

6. INSPECT FAN NO. 3 RELAY

(a) Remove the FAN No. 3 relay from the engine room relay block.





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

Standard Resistance:





(c) Reinstall the FAN No. 3 relay.

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 engine room relay block.

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

Standard Resistance (Check for Open):





(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) Disconnect the cooling fan motor connector.





(b) Check that the cooling fan motor operates smoothly when the battery is connected to the cooing fan motor connector.

(c) Measure the current while the motor is operating.

Standard Current:





Text in Illustration





(d) Reconnect the cooling fan motor connector.

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 - ENGINE ROOM RELAY BLOCK)

(a) Disconnect the cooling fan motor connector.

(b) Remove the FAN No. 1 relay and FAN No. 2 relay from the 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):





(d) Reconnect the cooling fan motor connector.

(e) Reinstall the FAN No. 1 relay and FAN No. 2 relay.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN MOTOR - ENGINE ROOM RELAY BLOCK)
OK -- Continue to next step.

11. INSPECT NO. 2 COOLING FAN MOTOR

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





(b) Check that the No. 2 cooling fan motor operates smoothly when the battery is connected to the No. 2 cooling fan motor connector.

(c) Measure the current while the motor is operating.

Standard Current:





Text in Illustration





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

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

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

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

(b) Remove the FAN No. 2 relay and FAN No. 3 relay from the 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):





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

(e) Reinstall the FAN No. 2 relay and FAN No. 3 relay.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 2 COOLING FAN MOTOR - ENGINE ROOM RELAY BLOCK)
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 relay and FAN No. 2 relay from the engine room relay block.

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

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





(c) Reinstall the FAN No. 1 relay and FAN No. 2 relay.

NG -- REPLACE ENGINE ROOM RELAY BLOCK

OK -- REPLACE ECM Removal

14. CHECK FUSE (ECU-IG NO. 1 FUSE VOLTAGE)

(a) Remove the ECU-IG No. 1 fuse from the instrument panel junction block assembly.





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

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

Standard Voltage:





Text in Illustration





(d) Reinstall the ECU-IG No. 1 fuse.

NG -- INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG1 NO. 1 RELAY)
OK -- Continue to next step.

15. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

(a) Disconnect the instrument panel junction block assembly connector.





(b) Remove the ECU-IG No. 1 fuse from the instrument panel junction block assembly.

(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 ECU-IG No. 1 fuse.

(e) Reconnect the instrument panel junction block assembly connector.

NG -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY
OK -- Continue to next step.

16. INSPECT FAN NO. 1 RELAY

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





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

Standard Resistance:





(c) Reinstall the FAN No. 1 relay.

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

17. INSPECT FAN NO. 2 RELAY

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





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

Standard Resistance:





(c) Reinstall the FAN No. 2 relay.

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

18. INSPECT FAN NO. 3 RELAY

(a) Remove the FAN No. 3 relay from the engine room relay block.





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

Standard Resistance:





(c) Reinstall the FAN No. 3 relay.

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

19. CHECK HARNESS AND CONNECTOR (ENGINE ROOM RELAY BLOCK - ECM)

(a) Remove the FAN No. 1 relay, FAN No. 2 relay and FAN No. 3 relay from the 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):





Standard Resistance (Check for Short):





(d) Reinstall the FAN No. 1 relay, FAN No. 2 relay and FAN No. 3 relay.

(e) Reconnect the ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE ROOM RELAY BLOCK - ECM)

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (ECU-IG NO. 1 FUSE - ENGINE ROOM RELAY BLOCK)

20. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG1 NO. 1 RELAY)

(a) Disconnect the instrument panel junction block assembly connector.





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

Standard Resistance:





Text in Illustration





(c) Reconnect the instrument panel junction block assembly connector.

NG -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG1 NO. 1 RELAY)
OK -- Continue to next step.

21. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG1 NO. 1 RELAY VOLTAGE)

(a) Disconnect the instrument panel junction block assembly connector.





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

Standard Voltage:





Text in Illustration





(c) Reconnect the instrument panel junction block assembly connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)
OK -- Continue to next step.

22. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - BODY GROUND)

(a) Disconnect the instrument panel junction block assembly connector.

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

Standard Resistance:





(c) Reconnect the instrument panel junction block assembly connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 NO. 1 RELAY - BODY GROUND)
OK -- Continue to next step.

23. CHECK HARNESS AND CONNECTOR (IG1 NO. 1 RELAY - POWER MANAGEMENT CONTROL ECU)

(a) Disconnect the instrument panel junction block assembly connector.

(b) Disconnect the power management control ECU connector.

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

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





(d) Reconnect the instrument panel junction block assembly connector.

(e) Reconnect the power management control ECU connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 NO. 1 RELAY - POWER MANAGEMENT CONTROL ECU)

OK -- CHECK SMART KEY SYSTEM How To Proceed With Troubleshooting
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