Cooling Fan Circuit

2AZ-FXE COOLING: COOLING FAN SYSTEM: Cooling Fan Circuit
- Cooling Fan Circuit

DESCRIPTION

The ECM (included in the hybrid vehicle control ECU) calculates an appropriate cooling fan speed based on the engine 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 fans. The cooling fan ECU controls the cooling fan speed based on the duty ratio signal sent from the ECM (included in the hybrid vehicle control ECU). By basing its control on the operating conditions, the ECM (included in the hybrid vehicle control ECU) can control the fan speed optimally using the cooling fan ECU, achieving both high cooling performance and quietness. The cooling fan speed is determined based on engine coolant temperature, air conditioner operating conditions, engine speed and vehicle speed.

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

(d) Check the operation of the cooling fans while operating it using the Techstream.

OK:





Result:





B -- INSPECT COOLING FAN MOTOR (COOLING FAN MOTOR AND NO. 2 COOLING FAN MOTOR)

C -- CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - COOLING FAN ECU)

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

2. INSPECT COOLING FAN MOTOR (COOLING FAN MOTOR AND NO. 2 COOLING FAN MOTOR)

(a) Disconnect the cooling fan motor and No. 2 cooling fan motor connectors.





(b) Connect a battery positive (+) lead to each terminal 2 of the cooling fan motor and No. 2 cooling fan motor connectors, and connect a battery negative (-) lead to each terminal 1 of the cooling fan motor and No. 2 cooling fan motor connectors.

OK:

The cooling fan motors operate.

Text in Illustration





Result:





(c) Reconnect the cooling fan motor connectors.

B -- REPLACE COOLING FAN MOTOR Removal

C -- REPLACE NO. 2 COOLING FAN MOTOR Removal
A -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU POWER SOURCE)

(a) Disconnect the cooling fan ECU 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 cooling fan ECU connector.

NG -- CHECK HARNESS AND CONNECTOR (COOLING FAN ECU - BODY GROUND)
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - COOLING FAN ECU)

(a) Disconnect the hybrid vehicle control ECU connector.

(b) Disconnect the cooling fan ECU connector.

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

Standard Resistance (Check for Short):





(d) Reconnect the cooling fan ECU connector.

(e) Reconnect the hybrid vehicle control ECU connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE COOLING FAN ECU Locations

5. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU - BODY GROUND)

(a) Disconnect the cooling fan ECU connector.

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

Standard Resistance (Check for Open):





(c) Reconnect the cooling fan ECU connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

6. INSPECT RELAY (FAN RELAY)

(a) Remove the FAN 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 relay.

NG -- REPLACE RELAY (FAN RELAY) Locations
OK -- Continue to next step.

7. CHECK HARNESS AND CONNECTOR (FAN RELAY POWER SOURCE)

(a) Remove the FAN relay from the engine room relay block.

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

Standard Voltage:





(c) Reinstall the FAN relay.

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

8. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU - FAN RELAY)

(a) Remove the FAN relay from the engine room relay block.

(b) Disconnect the cooling fan 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 cooling fan ECU connector.

(e) Reinstall the FAN relay.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU - FAN RELAY)
OK -- Continue to next step.

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

(a) Remove the FAN 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 relay.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN RELAY - BODY GROUND)

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN RELAY - MAIN BODY ECU)

10. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - COOLING FAN ECU)

(a) Disconnect the hybrid vehicle control ECU connector.

(b) Disconnect the cooling fan ECU connector.

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

Standard Resistance:





(d) Reconnect the cooling fan ECU connector.

(e) Reconnect the hybrid vehicle control ECU connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE COOLING FAN ECU Locations