Engine Cooling Fan System (diagnostics & Circuit Tests) Toyota Prius C I

PRECAUTION

1. IGNITION SWITCH EXPRESSIONS The type of ignition switch used on this model differs depending on the specifications of the vehicle. The expressions listed in the table below are used in this information. Expression Ignition Switch (Position) Power Switch (Condition) Ignition Switch off LOCK Off (Look) Ignition Switch ACC ACC On (ACC) Ignition Switch ON (IG) ON (IG) On (IG) Ignition switch ON (READY) ON (READY) On (Ready)
2. COOLING FAN SYSTEM NOTE: When the ignition switch is turned off and the engine temperature is high, the engine water pump assembly and cooling fans may operate for a maximum of 2 minutes depending on the auxiliary battery voltage. After turning the ignition switch off, keep hands and objects away from the fans when they are operating. HINT: If all of the following are met for a certain period of time during a few minutes immediately before the ignition switch is turned off, the cooling fans will continue to operate for a maximum of 2 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 ignition switch to 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. If the cooling fan motor does not operate, check the cooling fan circuit. Refer to «Cooling Fan Circuit»(/toyota/prius-c/i-2011-2015/remont/cooling-fan/#engine-cooling-fan-system-diagnostics-circuit-tests) .

DESCRIPTION

The ECM calculates an appropriate cooling fan speed based on the engine coolant temperature, inverter coolant temperature, air conditioning switch condition, refrigerant pressure, engine speed and vehicle speed, and sends the signals to the cooling fan ECU to regulate the cooling fan. The cooling fan ECU controls the 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 ECU, achieving both high cooling performance and quietness.

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 ignition switch to 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 fan while operating them using the Techstream. OK Techstream Operation Specified Condition ON Cooling fan operating OFF Cooling fan stopped Result Result Proceed to OK A NG (Cooling fan does not operate) B NG (Cooling fan does not stop) C B --> See step 2 C --> See step 11 A --> See step 13
2. INSPECT COOLING FAN MOTOR Inspect the cooling fan motor. Refer to «ON-VEHICLE INSPECTION»(/toyota/prius-c/i-2011-2015/remont/cooling-fan/#engine-cooling-system-service-information) . NG --> See step 14 OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU POWER SOURCE) Disconnect the cooling fan ECU connector. Turn the ignition switch to ON (IG). Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition A52-1 (+B1) - A52-3 (E1) Ignition switch ON (IG) 11 to 14 V TEXT IN ILLUSTRATION *a Front view of wire harness connector (to Cooling Fan ECU) NG --> See step 5 OK: Go to next step
4. CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU) Disconnect the ECM connector. Disconnect the cooling fan ECU connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition A40-45 (RFC) or A52-2 (SI) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - COOLING FAN ECU) OK --> See step 13
5. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU - BODY GROUND) Disconnect the cooling fan ECU connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition A52-3 (E1) - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU - BODY GROUND) OK: Go to next step
6. INSPECT COOLING FAN RELAY (FAN RELAY) Inspect the FAN relay. Refer to «ON-VEHICLE INSPECTION»(/toyota/prius-c/i-2011-2015/remont/cooling-fan/#engine-cooling-system-service-information) . NG --> REPLACE COOLING FAN RELAY (FAN RELAY) OK: Go to next step
7. CHECK HARNESS AND CONNECTOR (FAN RELAY POWER SOURCE) Remove the FAN relay from the No. 2 engine room relay block and No. 2 junction block assembly. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition 3 (FAN relay) - Body ground Ignition switch off 11 to 14 V TEXT IN ILLUSTRATION *1 No. 2 Engine Room Relay Block and No. 2 Junction Block Assembly *2 FAN Relay NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN RELAY - AUXILIARY BATTERY) OK: Go to next step
8. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU - FAN RELAY) Remove the FAN relay from the No. 2 engine room relay block and No. 2 junction block assembly. Disconnect the cooling fan ECU connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition A52-1 (+B1) - 5 (FAN relay) Always Below 1 ohms A52-1 (+B1) or 5 (FAN relay) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU - FAN RELAY) OK: Go to next step
9. CHECK HARNESS AND CONNECTOR (FAN RELAY - BODY GROUND) Remove the FAN relay from the No. 2 engine room relay block and No. 2 junction block assembly. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 2 (FAN relay) - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN RELAY - BODY GROUND) OK: Go to next step
10. CHECK HARNESS AND CONNECTOR (FAN RELAY - NO. 1 INTEGRATION RELAY) Remove the FAN relay from the No. 2 engine room relay block and No. 2 junction block assembly. Disconnect the No. 1 integration relay connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 1(FAN relay) - 2C-4 Always Below 1 ohms 1(FAN relay) or 2C-4 - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN RELAY - NO. 1 INTEGRATION RELAY) OK --> See step 15
11. CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU) Disconnect the ECM connector. Disconnect the cooling fan ECU connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition A40-45 (RFC) - A52-2 (SI) Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - COOLING FAN ECU) OK: Go to next step
12. 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 z4-1 - Body ground Always 10 kohms or higher TEXT IN ILLUSTRATION *a Component without harness connected (Cooling Fan Motor) NG --> See step 14 OK --> See step 13
13. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(/toyota/prius-c/i-2011-2015/remont/cooling-fan/#engine-cooling-fan-system-diagnostics-circuit-tests__problem-symptoms-table)
14. REPLACE COOLING FAN MOTOR. Refer to «REMOVAL»(/toyota/prius-c/i-2011-2015/remont/cooling-fan/#engine-cooling-system-service-information)
15. CHECK ECM POWER SOURCE CIRCUIT. Refer to «ECM Power Source Circuit»(/toyota/prius-c/i-2011-2015/remont/testing-diagnostics/#engine-control-system-diagnostic-codes-p1604-u0293-circuit-tests)

See also:
• INSPECTION
• ON-VEHICLE INSPECTION
• ECM Power Source Circuit
• Cooling Fan Circuit
• PROBLEM SYMPTOMS TABLE