Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000001HBGL
Model Year Start: 2020 Model: Corolla Prod Date Range: [01/2019 -           ]
Title: 2ZR-FXE (COOLING): COOLING FAN SYSTEM: Cooling Fan Circuit; 2020 - 2025 MY Corolla Corolla HV [01/2019 -        ]

Cooling Fan Circuit

DESCRIPTION

The ECM turns on or off the fan relays using signals calculated from the engine coolant temperature, air conditioning switch (on/off), air conditioning refrigerant pressure, engine speed and vehicle speed signals.

The ECM switches the circuit of the cooling fan motors between series and parallel by turning on or off the fan relays in order to control the speed of the cooling fan motors in two steps.

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 TECHSTREAM (CONTROL THE ENGINE COOLING FAN)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

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

Powertrain > Engine > Active Test

Tester Display

Control the Engine Cooling Fan

(e) Perform the Active Test according to the display on the Techstream.

OK:

Active Tester Operation

Fan Operation

HIGH

Cooling fans high speed operate

LOW

Cooling fans low speed operate

OFF

Cooling fans stop

OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

2.

CHECK HARNESS AND CONNECTOR (FANL - FANH POWER SOURCE)

(a) Disconnect the A46 ECM connector.

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

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A46-8 (FANH) - Body ground

Power switch on (IG)

11 to 14 V

A46-7 (FANL) - Body ground

Power switch on (IG)

11 to 14 V

*a

Front view of wire harness connector

(to ECM)

NG

GO TO STEP 12

OK

3.

CHECK HARNESS AND CONNECTOR (FAN NO. 1 RELAY AND FAN NO. 3 RELAY POWER SOURCE CIRCUIT)

(a) Remove the FAN NO. 1 relay from the No. 2 relay block.

(b) Remove the FAN NO. 3 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

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

*1

No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly

*2

No. 2 Relay Block

*3

FAN NO. 1 Relay

*4

FAN NO. 3 Relay

Standard Voltage:

Tester Connection

Condition

Specified Condition

3 (FAN NO. 1 relay) - Body ground

Always

11 to 14 V

3 (FAN NO. 3 relay) - Body ground

Always

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 1 RELAY AND FAN NO. 3 RELAY POWER SOURCE CIRCUIT)

OK

4.

INSPECT COOLING FAN RELAY (FAN NO. 1, FAN NO. 2 AND FAN NO. 3)

(a) Inspect the FAN NO. 1 relay, FAN NO. 2 relay and FAN NO. 3 relay.

Click here 2020 - 2025 MY Corolla Corolla HV [01/2019 -        ]; 2ZR-FXE (COOLING): RELAY: ON-VEHICLE INSPECTION

Result

Proceed to

OK

A

NG (FAN NO. 1 relay)

B

NG (FAN NO. 2 relay)

C

NG (FAN NO. 3 relay)

D

B

REPLACE FAN NO. 1 RELAY

C

REPLACE FAN NO. 2 RELAY

D

REPLACE FAN NO. 3 RELAY

A

5.

CHECK HARNESS AND CONNECTOR (FAN NO. 2 RELAY - BODY GROUND)

(a) Remove the FAN NO. 2 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

*1

No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly

*2

FAN NO. 2 Relay

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

5 (FAN NO. 2 relay) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 2 RELAY - BODY GROUND)

OK

6.

INSPECT COOLING FAN MOTOR RH

(a) Inspect the cooling fan motor RH.

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NG

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OK

7.

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

(a) Disconnect the A4 cooling fan motor RH connector.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

A4-1 - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN MOTOR RH - BODY GROUND)

OK

8.

CHECK HARNESS AND CONNECTOR (FAN NO. 1 RELAY AND FAN NO. 2 RELAY - COOLING FAN MOTOR RH)

(a) Disconnect the A4 cooling fan motor RH connector.

(b) Remove the FAN NO. 1 relay from the No. 2 relay block.

(c) Remove the FAN NO. 2 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

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

*1

No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly

*2

No. 2 Relay Block

*3

FAN NO. 1 Relay

*4

FAN NO. 2 Relay

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

A4-2 - 5 (FAN NO. 1 relay)

Always

Below 1 Ω

A4-2 - 4 (FAN NO. 2 relay)

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

A4-2 or 5 (FAN NO. 1 relay) - Body ground

Always

10 kΩ or higher

A4-2 or 4 (FAN NO. 2 relay) - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 1 RELAY AND FAN NO. 2 RELAY - COOLING FAN MOTOR RH)

OK

9.

INSPECT COOLING FAN MOTOR LH

(a) Inspect the cooling fan motor LH.

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NG

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OK

10.

CHECK HARNESS AND CONNECTOR (FAN NO. 2 RELAY AND FAN NO. 3 RELAY - COOLING FAN MOTOR LH)

(a) Disconnect the A5 cooling fan motor LH connector.

(b) Remove the FAN NO. 2 relay and FAN NO. 3 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

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

*1

No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly

*2

FAN NO. 2 Relay

*3

FAN NO. 3 Relay

-

-

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

A5-1 - 3 (FAN NO. 2 relay)

Always

Below 1 Ω

A5-2 - 5 (FAN NO. 3 relay)

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

A5-1 or 3 (FAN NO. 2 relay) - Body ground

Always

10 kΩ or higher

A5-2 or 5 (FAN NO. 3 relay) - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 2 RELAY AND FAN NO. 3 RELAY - COOLING FAN MOTOR LH)

OK

11.

CHECK HARNESS AND CONNECTOR (FAN NO. 1 RELAY - FAN NO. 2 RELAY)

(a) Remove the FAN NO. 1 relay from the No. 2 relay block.

(b) Remove the FAN NO. 2 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

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

*1

No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly

*2

No. 2 Relay Block

*3

FAN NO. 1 Relay

*4

FAN NO. 2 Relay

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

1 (FAN NO. 1 relay) - 1 (FAN NO. 2 relay)

Always

Below 1 Ω

2 (FAN NO. 1 relay) - 2 (FAN NO. 2 relay)

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

1 (FAN NO. 1 relay) or 1 (FAN NO. 2 relay) - Body ground

Always

10 kΩ or higher

2 (FAN NO. 1 relay) or 2 (FAN NO. 2 relay) - Body ground

Always

10 kΩ or higher

OK

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NG

REPAIR OR REPLACE NO. 2 RELAY BLOCK

12.

INSPECT COOLING FAN RELAY (FAN NO. 1, FAN NO. 2 AND FAN NO. 3)

(a) Inspect the FAN NO. 1 relay, FAN NO. 2 relay and FAN NO. 3 relay.

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Result

Proceed to

OK

A

NG (FAN NO. 1 relay)

B

NG (FAN NO. 2 relay)

C

NG (FAN NO. 3 relay)

D

B

REPLACE FAN NO. 1 RELAY

C

REPLACE FAN NO. 2 RELAY

D

REPLACE FAN NO. 3 RELAY

A

13.

CHECK HARNESS AND CONNECTOR (FAN NO. 1 RELAY, FAN NO. 2 RELAY AND FAN NO. 3 RELAY POWER SOURCE CIRCUIT)

(a) Remove the FAN NO. 1 relay from the No. 2 relay block.

(b) Remove the FAN NO. 2 relay and FAN NO. 3 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

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

*1

No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly

*2

No. 2 Relay Block

*3

FAN NO. 1 Relay

*4

FAN NO. 2 Relay

*5

FAN NO. 3 Relay

-

-

Standard Voltage:

Tester Connection

Condition

Specified Condition

1 (FAN NO. 1 relay) - Body ground

Always

11 to 14 V

1 (FAN NO. 2 relay) - Body ground

Always

11 to 14 V

1 (FAN NO. 3 relay) - Body ground

Always

11 to 14 V

OK

REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 1 RELAY, FAN NO. 2 RELAY AND FAN NO. 3 RELAY - ECM)

NG

14.

CHECK HARNESS AND CONNECTOR (FAN NO. 1 RELAY, FAN NO. 2 RELAY AND FAN NO. 3 RELAY - NO. 1 INTEGRATION RELAY)

(a) Remove the FAN NO. 1 relay from the No. 2 relay block.

(b) Remove the FAN NO. 2 relay and FAN NO. 3 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

(c) Remove the No. 1 integration relay from the No. 1 engine room relay block and No. 1 junction block assembly.

(d) Disconnect the 2B No. 1 integration relay connector.

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

*1

No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly

*2

No. 2 Relay Block

*3

FAN NO. 1 Relay

*4

FAN NO. 2 Relay

*5

FAN NO. 3 Relay

-

-

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

1 (FAN NO. 1 relay) - 2B-4

Always

Below 1 Ω

1 (FAN NO. 2 relay) - 2B-4

Always

Below 1 Ω

1 (FAN NO. 3 relay) - 2B-4

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

1 (FAN NO. 1 relay) or 2B-4 - Body ground

Always

10 kΩ or higher

1 (FAN NO. 2 relay) or 2B-4 - Body ground

Always

10 kΩ or higher

1 (FAN NO. 3 relay) or 2B-4 - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (FAN NO. 1 RELAY, FAN NO. 2 RELAY AND FAN NO. 3 RELAY - NO. 1 INTEGRATION RELAY)

OK

15.

INSPECT NO. 1 INTEGRATION RELAY (EFI-MAIN RELAY)

(a) Inspect the No. 1 integration relay.

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NG

REPAIR OR REPLACE NO. 1 INTEGRATION RELAY (EFI-MAIN RELAY)

OK

16.

CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY POWER SOURCE CIRCUIT)

(a) Remove the No. 1 integration relay from the No. 1 engine room relay block and No. 1 junction block assembly.

(b) Disconnect the 2B No. 1 integration relay connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

2B-3 - Body ground

Always

11 to 14 V

*a

Front view of wire harness connector

(to No. 1 Integration Relay)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 1 INTEGRATION RELAY POWER SOURCE CIRCUIT)

OK

17.

CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - BODY GROUND)

(a) Remove the No. 1 integration relay from the No. 1 engine room relay block and No. 1 junction block assembly.

(b) Disconnect the 2B No. 1 integration relay connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2B-5 - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 1 INTEGRATION RELAY - BODY GROUND)

OK

18.

CHECK HARNESS AND CONNECTOR (ECM - NO. 1 INTEGRATION RELAY)

(a) Disconnect the A46 ECM connector.

(b) Disconnect the 2B No. 1 integration relay connector.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

A46-46 (MREL) - 2B-6

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

A46-46 (MREL) or 2B-6 - Body ground

Always

10 kΩ or higher

OK

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NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - NO. 1 INTEGRATION RELAY)