Component Tests and General Diagnostics

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 circuits 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 ignition switch to ON.

(c) Turn the Techstream on.

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

(e) 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.





Text in Illustration





(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





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.





Text in Illustration





(b) Turn the ignition switch to ON.

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

Standard Voltage:





(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.





Text in Illustration





(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 ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE COOLING FAN ECU

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

(a) Disconnect the cooling fan ECU connector.





Text in Illustration





(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)

(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)
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.





Text in Illustration





(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.





Text in Illustration





(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
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.





Text in Illustration





(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

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN RELAY - IG1 NO. 2 RELAY)

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

(a) Disconnect the ECM connector.





Text in Illustration





(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):





(d) Reconnect the cooling fan ECU.

(e) Reconnect the ECM.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE COOLING FAN ECU