Cooling Fan Circuit

2GR-FE COOLING: COOLING FAN SYSTEM: Cooling Fan Circuit
- Cooling Fan Circuit

DESCRIPTION

The ECM 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. 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. 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 circuit related to this system before performing the following inspection procedure.

PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE COOLING FAN)

(a) Connect the Techstream to the DLC3.

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

(c) Enter the following menus: Powertrain / Engine / Active Test / Control the Cooling Fan.

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

OK:





Result:





C -- CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU)

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

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

OK:

The cooling fan motor and No. 2 cooling fan motors operate.

Result:





Text in Illustration





C -- REPLACE NO. 2 COOLING FAN MOTOR Removal

B -- REPLACE 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 engine 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 (ECM - COOLING FAN ECU)

(a) Disconnect the ECM 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):





Text in Illustration





(d) Reconnect the cooling fan ECU connector.

(e) Reconnect the ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - COOLING FAN ECU)

OK -- REPLACE COOLING FAN ECU

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):





Text in Illustration





(c) Reconnect the cooling fan ECU connector.

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

6. INSPECT RELAY (RDI FAN NO. 1)

(a) Remove the RDI 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 RDI FAN No. 1 relay.

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

7. CHECK HARNESS AND CONNECTOR (RDI FAN NO. 1 RELAY POWER SOURCE)

(a) Remove the RDI FAN No. 1 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 RDI FAN No. 1 relay.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (RDI FAN NO. 1 RELAY - BATTERY)
OK -- Continue to next step.

8. CHECK HARNESS AND CONNECTOR (COOLING FAN ECU - RDI FAN NO. 1 RELAY)

(a) Remove the RDI FAN No. 1 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):





Text in Illustration





(d) Reconnect the cooling fan ECU connector.

(e) Reinstall the RDI FAN No. 1 relay.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU - RDI FAN NO. 1 RELAY)
OK -- Continue to next step.

9. CHECK HARNESS AND CONNECTOR (RDI FAN NO. 1 RELAY - BODY GROUND)

(a) Remove the RDI 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 (Check for Open):





Text in Illustration





(c) Reinstall the RDI FAN No. 1 relay.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (RDI FAN NO. 1 RELAY - BODY GROUND)

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (RDI FAN NO. 1 RELAY - EFI MAIN RELAY)

10. CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU)

(a) Disconnect the ECM 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 Open):





Text in Illustration





(d) Reconnect the cooling fan ECU.

(e) Reconnect the ECM.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - COOLING FAN ECU)

OK -- REPLACE COOLING FAN ECU