Engine Cooling Fan (diagnostics & Circuit Tests) (except Phv) Toyota Prius PHV pre-III

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PROBLEM SYMPTOMS TABLE

HINT

1. Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
2. Inspect the fuses related to this system before inspecting the suspected areas below.

COOLING FAN SYSTEM

ON-VEHICLE INSPECTION

1. INSPECT COOLING FAN SYSTEM Connect the Techstream to the DLC3. Turn the power switch on (IG). Enter the following menus: Powertrain / Engine / Active Test / Control the Electric Cooling Fan. Check operation of the cooling fans while operating them using the Techstream. If the cooling fans do not operate, check the cooling fan circuit. Refer to «Cooling Fan Circuit»(/toyota/prius-phv/pre-iii-2010-2011/remont/cooling-fan/#engine-cooling-fan-diagnostics-circuit-tests-except-phv) .

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. Refer to SYSTEM DIAGRAM .

INSPECTION PROCEDURE

Note. Inspect the fuses for circuits related to this system before performing the following inspection procedure.

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1. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE ELECTRIC COOLING FAN) Connect the Techstream to the DLC3. Turn the power switch on (IG). Turn the Techstream on. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Electric Cooling Fan. OK Tester Operation Specified Condition ON Fans operate OFF Fans do not operate NG --> See step 2 OK --> See step 24
2. INSPECT ECM (FANL AND FANH VOLTAGE) Disconnect the ECM connector. TEXT IN ILLUSTRATION *1 Front view of wire harness connector (to ECM) Turn the power switch on (IG). Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Switch Condition Specified Condition A57-22 (FANH) - Body ground Power switch on (IG) 11 to 14 V A57-21 (FANL) - Body ground Power switch on (IG) 11 to 14 V Reconnect the ECM connector. NG --> See step 14 OK: Go to next step
3. INSPECT ENGINE ROOM RELAY BLOCK (FAN NO. 1 RELAY AND FAN NO. 3 RELAY VOLTAGE) Remove the FAN No. 1 relay and FAN No. 3 relay from the engine room relay block. TEXT IN ILLUSTRATION *1 Engine Room Relay Block 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 14 V 5 (FAN No. 3 relay) - Body ground Always 11 to 14 V Reinstall the FAN No. 1 relay and FAN No. 3 relay. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - ENGINE ROOM RELAY BLOCK) OK: Go to next step
4. INSPECT FAN NO. 1 RELAY Remove the FAN No. 1 relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 3 - 5 Battery voltage is not applied between terminals 1 and 2 10 kohms or higher Battery voltage is applied between terminals 1 and 2 Below 1 ohms Reinstall the FAN No. 1 relay. NG --> REPLACE FAN NO. 1 RELAY OK: Go to next step
5. INSPECT FAN NO. 2 RELAY Remove the FAN No. 2 relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 3 - 4 Battery voltage is not applied between terminals 1 and 2 Below 1 ohms Battery voltage is applied between terminals 1 and 2 10 kohms or higher 3 - 5 Battery voltage is not applied between terminals 1 and 2 10 kohms or higher Battery voltage is applied between terminals 1 and 2 Below 1 ohms Reinstall the FAN No. 2 relay. NG --> REPLACE FAN NO. 2 RELAY OK: Go to next step
6. INSPECT FAN NO. 3 RELAY Remove the FAN No. 3 relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 3 - 5 Battery voltage is not applied between terminals 1 and 2 10 kohms or higher Battery voltage is applied between terminals 1 and 2 Below 1 ohms Reinstall the FAN No. 3 relay. NG --> REPLACE FAN NO. 3 RELAY OK: Go to next step
7. CHECK HARNESS AND CONNECTOR (FAN NO. 2 RELAY - BODY GROUND) Remove the FAN No. 2 relay from the engine room relay block. TEXT IN ILLUSTRATION *1 Engine Room Relay Block 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 ohms Reinstall the FAN No. 2 relay. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 2 RELAY - BODY GROUND) OK: Go to next step
8. INSPECT COOLING FAN MOTOR Disconnect the cooling fan motor connector. TEXT IN ILLUSTRATION *1 Component without harness connected (Cooling Fan Motor) Check that the cooling fan motor operates smoothly when the battery is connected to the cooing fan motor connector. Measure the current while the motor is operating. Standard Current Tester Connection Condition Specified Condition 1 - 2 Always 11.2 to 14.5 A Reconnect the cooling fan motor connector. NG --> See step 25 OK: Go to next step
9. CHECK HARNESS AND CONNECTOR (COOLING FAN MOTOR - BODY GROUND) Disconnect the cooling fan motor connector. TEXT IN ILLUSTRATION *1 Front view of wire harness connector (to Cooling Fan Motor) Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open) Tester Connection Condition Specified Condition A5-1 - Body ground Always Below 1 ohms Reconnect the cooling fan motor connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN MOTOR - BODY GROUND) OK: Go to next step
10. CHECK HARNESS AND CONNECTOR (COOLING FAN MOTOR - ENGINE ROOM RELAY BLOCK) Disconnect the cooling fan motor connector. TEXT IN ILLUSTRATION *1 Front view of wire harness connector (to Cooling Fan Motor) *2 Engine Room Relay Block Remove the FAN No. 1 relay and FAN No. 2 relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open) Tester Connection Condition Specified Condition A5-2 - 5 (FAN No. 1 relay) Always Below 1 ohms A5-2 - 4 (FAN No. 2 relay) Always Below 1 ohms Standard Resistance (Check for Short) Tester Connection Condition Specified Condition A5-2 or 5 (FAN No. 1 relay) - Body ground Always 10 kohms or higher A5-2 or 4 (FAN No. 2 relay) - Body ground Always 10 kohms or higher Reconnect the cooling fan motor connector. 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: Go to next step
11. INSPECT NO. 2 COOLING FAN MOTOR Disconnect the No. 2 cooling fan motor connector. TEXT IN ILLUSTRATION *1 Component without harness connected (No. 2 Cooling Fan Motor) Check that the No. 2 cooling fan motor operates smoothly when the battery is connected to the No. 2 cooling fan motor connector. Measure the current while the motor is operating. Standard Current Tester Connection Condition Specified Condition 1 - 2 Always 7.4 to 10.9 A Reconnect the No. 2 cooling fan motor connector. NG --> See step 26 OK: Go to next step
12. CHECK HARNESS AND CONNECTOR (NO. 2 COOLING FAN MOTOR - ENGINE ROOM RELAY BLOCK) Disconnect the No. 2 cooling fan motor connector. TEXT IN ILLUSTRATION *1 Front view of wire harness connector (to No. 2 Cooling Fan Motor) *2 Engine Room Relay Block Remove the FAN No. 2 relay and FAN No. 3 relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open) Tester Connection Condition Specified Condition A6-1 - 3 (FAN No. 2 relay) Always Below 1 ohms A6-2 - 3 (FAN No. 3 relay) Always Below 1 ohms Standard Resistance (Check for Short) Tester Connection Condition Specified Condition A6-1 or 3 (FAN No. 2 relay) - Body ground Always 10 kohms or higher A6-2 or 3 (FAN No. 3 relay) - Body ground Always 10 kohms or higher Reconnect the No. 2 cooling fan motor connector. 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: Go to next step
13. INSPECT ENGINE ROOM RELAY BLOCK (FAN NO. 1 RELAY - FAN NO. 2 RELAY) Remove the FAN No. 1 relay and FAN No. 2 relay from the engine room relay block. TEXT IN ILLUSTRATION *1 Engine Room Relay Block 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 ohms 2 (FAN No. 1 relay) - 2 (FAN No. 2 relay) Always Below 1 ohms 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 kohms or higher 2 (FAN No. 1 relay) or 2 (FAN No. 2 relay) - Body ground Always 10 kohms or higher Reinstall the FAN No. 1 relay and FAN No. 2 relay. NG --> REPLACE ENGINE ROOM RELAY BLOCK OK --> See step 27
14. CHECK FUSE (ECU-IG NO. 1 FUSE VOLTAGE) Remove the ECU-IG No. 1 fuse from the instrument panel junction block. TEXT IN ILLUSTRATION *1 Driver Side Junction Block Turn the power switch on (IG). Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Switch Condition Specified Condition 1 (ECU-IG No. 1 fuse) - Body ground Power switch on (IG) 11 to 14 V Reinstall the ECU-IG No. 1 fuse. NG --> See step 20 OK: Go to next step
15. INSPECT DRIVER SIDE JUNCTION BLOCK ASSEMBLY Disconnect the driver side junction block assembly connector. TEXT IN ILLUSTRATION *1 Component without harness connected (Driver Side Junction Block Assembly) *2 Driver Side Junction Block Assembly Remove the ECU-IG No. 1 fuse from the driver side junction block assembly. Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open) Tester Connection Condition Specified Condition 2C-30 - 2 (ECU-IG No. 1) Always Below 1 ohms Standard Resistance (Check for Short) Tester Connection Condition Specified Condition 2C-30 or 2 (ECU-IG No. 1) - Body ground Always 10 kohms or higher Reconnect the ECU-IG No. 1 fuse. Reconnect the Driver side junction block assembly connector. NG --> REPLACE DRIVER SIDE JUNCTION BLOCK ASSEMBLY OK: Go to next step
16. INSPECT FAN NO. 1 RELAY Remove the FAN No. 1 relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 3 - 5 Battery voltage is not applied between terminals 1 and 2 10 kohms or higher Battery voltage is applied between terminals 1 and 2 Below 1 ohms Reinstall the FAN No. 1 relay. NG --> REPLACE FAN NO. 1 RELAY OK: Go to next step
17. INSPECT FAN NO. 2 RELAY Remove the FAN No. 2 relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 3 - 4 Battery voltage is not applied between terminals 1 and 2 Below 1 ohms Battery voltage is applied between terminals 1 and 2 10 kohms or higher 3 - 5 Battery voltage is not applied between terminals 1 and 2 10 kohms or higher Battery voltage is applied between terminals 1 and 2 Below 1 ohms Reinstall the FAN No. 2 relay. NG --> REPLACE FAN NO. 2 RELAY OK: Go to next step
18. INSPECT FAN NO. 3 RELAY Remove the FAN No. 3 relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 3 - 5 Battery voltage is not applied between terminals 1 and 2 10 kohms or higher Battery voltage is applied between terminals 1 and 2 Below 1 ohms Reinstall the FAN No. 3 relay. NG --> REPLACE FAN NO. 3 RELAY OK: Go to next step
19. CHECK HARNESS AND CONNECTOR (ENGINE ROOM RELAY BLOCK - ECM) Remove the FAN No. 1 relay, FAN No. 2 relay and FAN No. 3 relay from the engine room relay block. TEXT IN ILLUSTRATION *1 Front view of wire harness connector (to ECM) *2 Engine Room Relay Block Disconnect the ECM connector. 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) - A57-22 (FANH) Always Below 1 ohms 2 (FAN No. 2 relay) - A57-22 (FANH) Always Below 1 ohms 2 (FAN No. 3 relay) - A57-21 (FANL) Always Below 1 ohms Standard Resistance (Check for Short) Tester Connection Condition Specified Condition 2 (FAN No. 1 relay) or A57-22 (FANH) - Body ground Always 10 kohms or higher 2 (FAN No. 2 relay) or A57-22 (FANH) - Body ground Always 10 kohms or higher 2 (FAN No. 3 relay) or A57-21 (FANL) - Body ground Always 10 kohms or higher Reinstall the FAN No. 1 relay, FAN No. 2 relay and FAN No. 3 relay. 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 DRIVER SIDE JUNCTION BLOCK ASSEMBLY (IG1 NO. 1 RELAY) Disconnect the driver side junction block assembly connector. TEXT IN ILLUSTRATION *1 Component without harness connected (to Driver Side Junction Block Assembly) Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 2E-1 - 2C-30 Battery voltage is not applied between terminals 2B-25 - 2B-6 10 kohms or higher Battery voltage is applied between terminals 2B-25 - 2B-6 Below 1 ohms Reconnect the driver side junction block assembly connector. NG --> REPLACE DRIVER SIDE JUNCTION BLOCK ASSEMBLY (IG1 NO. 1 RELAY) OK: Go to next step
21. INSPECT DRIVER SIDE JUNCTION BLOCK ASSEMBLY (IG1 NO. 1 RELAY VOLTAGE) Disconnect the driver side junction block assembly connector. TEXT IN ILLUSTRATION *1 Driver Side Junction Block Assembly *2 Front view of wire harness connector (to Driver Side Junction Block Assembly) Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition 2E-1 - Body ground Always 11 to 14 V Reconnect the driver side junction block assembly connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - DRIVER SIDE JUNCTION BLOCK ASSEMBLY) OK: Go to next step
22. CHECK HARNESS AND CONNECTOR (DRIVER SIDE JUNCTION BLOCK ASSEMBLY - BODY GROUND) Disconnect the driver side junction block assembly connector. TEXT IN ILLUSTRATION *1 Driver Side Junction Block Assembly *2 Front view of wire harness connector (to Driver Side Junction Block Assembly) Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 2B-6 - Body ground Always Below 1 ohms Reconnect the driver side junction block assembly connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 NO. 1 RELAY - BODY GROUND) OK: Go to next step
23. CHECK HARNESS AND CONNECTOR (IG1 NO. 1 RELAY - POWER MANAGEMENT CONTROL ECU) Disconnect the driver side junction block assembly connector. TEXT IN ILLUSTRATION *1 Front view of wire harness connector (to Power Management Control ECU) *2 Driver Side Junction Block Assembly *3 Front view of wire harness connector (to Driver Side Junction Block Assembly) - - Disconnect the power management control ECU connector. Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open) Tester Connection Condition Specified Condition L6-2 (IG1D) - 2B-25 Always Below 1 ohms Standard Resistance (Check for Short) Tester Connection Condition Specified Condition L6-2 (IG1D) or 2B-25 - Body ground Always 10 kohms or higher Reconnect the driver side junction block assembly connector. Reconnect the power management control ECU connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 NO. 1 RELAY - POWER MANAGEMENT CONTROL ECU) OK --> See step 28
24. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(/toyota/prius-phv/pre-iii-2010-2011/remont/cooling-fan/#engine-cooling-fan-diagnostics-circuit-tests-except-phv__problem-symptoms-table)
25. REPLACE COOLING FAN MOTOR. Refer to «REMOVAL»(/toyota/prius-phv/pre-iii-2010-2011/remont/cooling-fan/#engine-cooling-system-service-information-except-phv)
26. REPLACE NO. 2 COOLING FAN MOTOR. Refer to «REMOVAL»(/toyota/prius-phv/pre-iii-2010-2011/remont/cooling-fan/#engine-cooling-system-service-information-except-phv)
27. REPLACE ECM. Refer to «REMOVAL»(/toyota/prius-phv/pre-iii-2010-2011/remont/engine-control-systems/#engine-control-system-service-information-except-phv)
28. CHECK SMART KEY SYSTEM. Refer to «HOW TO PROCEED WITH TROUBLESHOOTING»(/toyota/prius-phv/pre-iii-2010-2011/remont/starter/#smart-key-system-keyless-start-diagnsostics-introduction-except-phv__how-to-proceed-with-troubleshooting)

See also:
• ON-VEHICLE INSPECTION
• HOW TO PROCEED WITH TROUBLESHOOTING
• REMOVAL
• HOW TO PROCEED WITH TROUBLESHOOTING
• Cooling Fan Circuit
• PROBLEM SYMPTOMS TABLE