Engine Cooling System [diagnostics & Circuit Tests] Toyota Prius V I

PRECAUTION

Note. When the power switch is turned off and the engine temperature is high, the engine water pump assembly and cooling fans may operate for a maximum of 3 minutes depending on the auxiliary battery voltage. After turning the power switch off, keep hands and objects away from the fans when they are operating.

HINT

1. If all of the following are met for a certain period of time during a few minutes immediately before the power switch is turned off, the cooling fans will continue to operate for a maximum of 3 minutes after the engine is stopped. This is performed to ensure restartability. The Techstream indicates a very high coolant temperature. The Techstream indicates a high outside air temperature.

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PROBLEM SYMPTOMS TABLE

HINT

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.

COOLING FAN SYSTEM

ON-VEHICLE INSPECTION

1. INSPECT COOLING FAN SYSTEM 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. 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-v/i-2011-2014/remont/cooling-fan/#engine-cooling-system-diagnostics-circuit-tests) .

DESCRIPTION

The ECM turns the fan relays on or off 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 the fan relays on or off 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. Check the operation of the cooling fans while operating them using the Techstream. OK Techstream Operation Specified Condition ON Fans operate OFF Fans do not operate NG --> See step 2 OK --> See step 15
2. INSPECT ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY (FAN NO. 1 RELAY, FAN NO. 2 RELAY AND FAN NO. 3 RELAY VOLTAGE) Remove the FAN No. 1 relay, FAN No. 2 relay and FAN No. 3 relay from the engine room relay block and junction block assembly. Turn the power switch on (IG). Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition 1 (FAN No. 1 relay) - Body ground Power switch on (IG) 11 to 14 V 1 (FAN No. 2 relay) - Body ground Power switch on (IG) 11 to 14 V 1 (FAN No. 3 relay) - Body ground Power switch on (IG) 11 to 14 V TEXT IN ILLUSTRATION *1 Engine Room Relay Block and Junction Block Assembly *2 FAN No. 1 Relay *3 FAN No. 2 Relay *4 FAN No. 3 Relay NG --> See step 14 OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY - ECM) Remove the FAN No. 1 relay, FAN No. 2 relay and FAN No. 3 relay from the engine room relay block and junction block assembly. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below. Standard Resistance 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 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 NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY - ECM) OK: Go to next step
4. INSPECT ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY (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 and junction block assembly. 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 Power switch off 11 to 14 V 5 (FAN No. 3 relay) - Body ground Power switch off 11 to 14 V TEXT IN ILLUSTRATION *1 Engine Room Relay Block and Junction Block Assembly *2 FAN No. 1 Relay *3 FAN No. 3 Relay NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY) OK: Go to next step
5. INSPECT FAN NO. 1 RELAY Inspect the FAN No. 1 relay. Refer to «ON-VEHICLE INSPECTION»(/toyota/prius-v/i-2011-2014/remont/cooling-fan/#engine-cooling-system-service-information) . NG --> REPLACE FAN NO. 1 RELAY OK: Go to next step
6. INSPECT FAN NO. 2 RELAY Inspect the FAN No. 2 relay. Refer to «ON-VEHICLE INSPECTION»(/toyota/prius-v/i-2011-2014/remont/cooling-fan/#engine-cooling-system-service-information) . NG --> REPLACE FAN NO. 2 RELAY OK: Go to next step
7. INSPECT FAN NO. 3 RELAY Inspect the FAN No. 3 relay. Refer to «ON-VEHICLE INSPECTION»(/toyota/prius-v/i-2011-2014/remont/cooling-fan/#engine-cooling-system-service-information) . NG --> REPLACE FAN NO. 3 RELAY OK: Go to next step
8. CHECK HARNESS AND CONNECTOR (FAN NO. 2 RELAY - BODY GROUND) Remove the FAN No. 2 relay from the engine room relay block and junction block assembly. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 5 (FAN No. 2 relay) - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 2 RELAY - BODY GROUND) OK: Go to next step
9. INSPECT COOLING FAN MOTOR Inspect the cooling fan motor. Refer to «ON-VEHICLE INSPECTION»(/toyota/prius-v/i-2011-2014/remont/cooling-fan/#engine-cooling-system-service-information) . NG --> See step 16 OK: Go to next step
10. CHECK HARNESS AND CONNECTOR (COOLING FAN MOTOR - BODY GROUND) Disconnect the cooling fan motor connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition A5-1 - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN MOTOR - BODY GROUND) OK: Go to next step
11. CHECK HARNESS AND CONNECTOR (COOLING FAN MOTOR - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY) Disconnect the cooling fan motor connector. Remove the FAN No. 1 relay and FAN No. 2 relay from the engine room relay block and junction block assembly. Measure the resistance according to the value(s) in the table below. Standard Resistance 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 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 HINT: Make sure that there are no short circuits to the auxiliary battery. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN MOTOR - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY) OK: Go to next step
12. INSPECT NO. 2 COOLING FAN MOTOR Inspect the No. 2 cooling fan motor. Refer to «ON-VEHICLE INSPECTION»(/toyota/prius-v/i-2011-2014/remont/cooling-fan/#engine-cooling-system-service-information) . NG --> See step 17 OK: Go to next step
13. CHECK HARNESS AND CONNECTOR (NO. 2 COOLING FAN MOTOR - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY) Disconnect the No. 2 cooling fan motor connector. Remove the FAN No. 2 relay and FAN No. 3 relay from the engine room relay block and junction block assembly. Measure the resistance according to the value(s) in the table below. Standard Resistance 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 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 HINT: Make sure that there are no short circuits to the auxiliary battery. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 2 COOLING FAN MOTOR - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY) OK --> See step 19
14. CHECK HARNESS AND CONNECTOR (ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY - NO. 2 INTEGRATION RELAY) Remove the FAN No. 1 relay, FAN No. 2 relay and FAN No. 3 relay from the engine room relay block and junction block assembly. Disconnect the No. 2 integration relay connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 1 (FAN No. 1 relay) - 1B-4 Always Below 1 ohms 1 (FAN No. 2 relay) - 1B-4 Always Below 1 ohms 1 (FAN No. 3 relay) - 1B-4 Always Below 1 ohms 1 (FAN No. 1 relay) or 1B-4 - Body ground Always 10 kohms or higher 1 (FAN No. 2 relay) or 1B-4 - Body ground Always 10 kohms or higher 1 (FAN No. 3 relay) or 1B-4 - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY - NO. 2 INTEGRATION RELAY) OK --> See step 18
15. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(/toyota/prius-v/i-2011-2014/remont/cooling-fan/#engine-cooling-system-diagnostics-circuit-tests__problem-symptoms-table)
16. REPLACE COOLING FAN MOTOR. Refer to «REMOVAL»(/toyota/prius-v/i-2011-2014/remont/cooling-fan/#engine-cooling-system-service-information)
17. REPLACE NO. 2 COOLING FAN MOTOR. Refer to «REMOVAL»(/toyota/prius-v/i-2011-2014/remont/cooling-fan/#engine-cooling-system-service-information)
18. CHECK ECM POWER SOURCE CIRCUIT. Refer to «ECM Power Source Circuit»(/toyota/prius-v/i-2011-2014/remont/testing-diagnostics/#engine-control-system-diagnostic-codes-circuit-tests)
19. REPLACE ECM. Refer to «REMOVAL»(/toyota/prius-v/i-2011-2014/remont/testing-diagnostics/#engine-control-system-service-information)

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