Toyota Corolla Cross Owners & Service Manuals

Toyota Corolla Cross: Cooling Fan Circuit

Toyota Corolla Cross (2022-2024) Service Manual / Engine & Hybrid System / M20a-fks (cooling) / Cooling Fan System / Cooling Fan Circuit

DESCRIPTION

The ECM calculates an appropriate cooling fan speed based on the engine coolant temperature, air conditioning switch status, refrigerant pressure, engine speed and vehicle speed, and sends a signal to the cooling fan ECU (fan with motor assembly). The cooling fan ECU (fan with motor assembly) steplessly control the speed of the cooling fan based on the duty cycle signal sent from the ECM. By sending signals to the cooling fan ECU (fan with motor assembly) in accordance with the driving conditions and by controlling the cooling fan speed optimally with the ECM, both high cooling performance and quietness are ensured.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • Before replacing the ECM, refer to Service Bulletin.

PROCEDURE

1.

PERFORM ACTIVE TEST USING GTS (CONTROL THE ENGINE COOLING FAN DUTY RATIO)

(a) Connect the GTS to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the GTS on.

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

Powertrain > Engine > Active Test

Tester Display

Control the Engine Cooling Fan

(e) Check the operation of the cooling fan while operating it using the GTS.

OK:

Tester Operation

Fan Operation

Low/High

Cooling fan operates

OFF

Cooling fan stops

Result

Proceed to

OK

A

Cooling fan does not operate

B

Cooling fan does not stop

C
A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

C

GO TO STEP 10

B

2.

INSPECT COOLING FAN ECU

(a) Inspect the cooling fan motor.

Click here

NG

REPLACE COOLING FAN MOTOR

OK

3.

CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

(a) Disconnect the A101 cooling fan ECU connector.

(b) Turn the ignition switch to ON.

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

Standard Voltage:

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

Tester Connection

Condition

Specified Condition

A101-1(+B1) - A101-3(E1)

Ignition switch ON

11 to 14 V

*a

Front view of wire harness connector

(to Cooling fan ECU)
NG

GO TO STEP 5

OK

4.

CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU)

(a) Disconnect the A182 ECM connector.

(b) Disconnect the A101 cooling fan ECU connector.

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

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

A182-32(RFC) or A101-2(SI) - Body ground

Always

10 kΩ or higher
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

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

5.

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

(a) Disconnect the A101 cooling fan ECU connector.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

A101-3(E1) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU - BODY GROUND)
OK

6.

INSPECT FAN-MAIN RELAY

(a) Inspect the FAN-MAIN relay.

Click here

NG

REPLACE FAN-MAIN RELAY
OK

7.

INSPECT HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

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

*1

Engine Room Relay Block

*2

FAN-MAIN Relay

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

3 (FAN-MAIN relay) - Body ground

Always

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN-MAIN RELAY - AUXILIARY BATTERY)
OK

8.

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

(a) Disconnect the A101 cooling fan ECU connector.

(b) Remove the FAN-MAIN relay from the engine room relay block.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

A101-1(+B1) - 5 (FAN-MAIN relay)

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

A101-1 (+B1) or 5 (FAN-MAIN relay) - Body ground

Always

10 kΩ or higher
NG

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

9.

CHECK HARNESS AND CONNECTOR (FAN MAIN RELAY - BODY GROUND)

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2 (FAN-MAIN relay) - Body ground

Always

Below 1 Ω
OK

REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN RELAY POWER SOURCE CIRCUIT)
NG

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

10.

CHECK HARNESS AND CONNECTOR (ECM - COOLING FAN ECU)

(a) Disconnect the A182 ECM connector.

(b) Disconnect the A101 cooling fan ECU connector.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

A182-65(RFC) - A101-2(SI)

Always

Below 1 Ω
NG

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

11.

CHECK HARNESS AND CONNECTOR (COOLING FAN MOTOR - BODY GROUND)

(a) Disconnect the cooling fan motor connector.

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

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

1(-) - Body ground

Always

10 kΩ or higher
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

REPLACE COOLING FAN MOTOR

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