1ar-fe Cooling

Cooling Fan Circuit

~9min read
DESCRIPTION

The ECM turns on or off the fan relays using signals calculated from the engine coolant temperature, air conditioning (ON/OFF), air conditioner 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

Refer to System Diagram (See page ).


CAUTION / NOTICE / HINT

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 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 it using the Techstream.

OK:

Tester Operation

Specified Condition

ON

Cooling fans operate

OFF

Cooling fans stop

Result

Proceed to

OK

A

NG (Cooling fans do not operate)

B

NG (Cooling fans do not stop)

C


A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE


C

GO TO STEP 15

B
  1. CHECK HARNESS AND CONNECTOR (EFI MAIN RELAY - FAN NO. 1, NO. 2 OR NO. 3 RELAY)

(a) Remove the FAN NO. 1, FAN NO. 2 and FAN NO. 3 relays from the engine room relay block and junction block assembly.


(b) Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

1 (FAN NO. 1 relay) - Body ground

Ignition switch ON

11 to 14 V

1 (FAN NO. 2 relay) - Body ground

Ignition switch ON

11 to 14 V

1 (FAN NO. 3 relay) - Body ground

Ignition switch ON

11 to 14 V

Text in Illustration

*1

Engine Room Relay Block and Junction Block Assembly

(d) Reinstall the FAN NO. 1, FAN NO. 2 and FAN NO. 3 relays.


NG

REPLACE ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY

OK
  1. INSPECT ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY (FAN NO. 1 OR NO. 3 RELAY VOLTAGE)

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


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

Standard Voltage:

Tester Connection

Condition

Specified Condition

3 (FAN NO. 1 relay) - Body ground

Always

11 to 14 V

5 (FAN NO. 3 relay) - Body ground

Always

11 to 14 V

Text in Illustration

*1

Engine Room Relay Block and Junction Block Assembly

(c) Reinstall the FAN NO. 1 and FAN NO. 3 relays.


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - FAN NO. 1 OR NO. 3 RELAY)

OK
  1. INSPECT FAN NO. 1 RELAY

(a) Inspect the FAN NO. 1 relay (See page
).


NG

REPLACE FAN NO. 1 RELAY

OK
  1. INSPECT FAN NO. 2 RELAY

(a) Inspect the FAN NO. 2 relay (See page
).


NG

REPLACE FAN NO. 2 RELAY

OK
  1. INSPECT FAN NO. 3 RELAY

(a) Inspect the FAN NO. 3 relay (See page
).


NG

REPLACE FAN NO. 3 RELAY

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

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

(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

Text in Illustration

*1

Engine Room Relay Block and Junction Block Assembly

(c) Reinstall the FAN NO. 2 relay.


NG

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

OK
  1. INSPECT NO. 2 COOLING FAN MOTOR

(a) Inspect the No. 2 cooling fan motor (See page ).



NG

REPLACE NO. 2 COOLING FAN MOTOR

OK
  1. CHECK HARNESS AND CONNECTOR (NO. 2 COOLING FAN MOTOR - BODY GROUND)

(a) Disconnect the No. 2 cooling fan motor connector.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

A48-1 - Body ground

Always

Below 1 Ω

Text in Illustration

*a

Front view of wire harness connector

(No. 2 cooling Fan Motor)

(c) Reconnect the No. 2 cooling fan motor connector.


NG

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

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

(a) Disconnect the No. 2 cooling fan motor connector.


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

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

A48-2 - 5 (FAN NO. 1 relay)

Always

Below 1 Ω

A48-2 - 4 (FAN NO. 2 relay)

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

A48-2 or 5 (FAN NO. 1 relay) or 4 (FAN NO. 2 relay) - Body ground

Always

10 kΩ or higher

Text in Illustration

*1

Engine Room Relay Block and Junction Block Assembly

*a

Front view of wire harness connector

(No. 2 cooling Fan Motor)

(d) Reconnect the No. 2 cooling fan motor connector.

(e) Reinstall the FAN NO. 1 and FAN NO. 2 relays.


NG

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

OK
  1. INSPECT COOLING FAN MOTOR

(a) Inspect the cooling fan motor (See page
).


NG

REPLACE COOLING FAN MOTOR

OK
  1. CHECK HARNESS AND CONNECTOR (COOLING FAN MOTOR - FAN NO. 2 OR NO. 3 RELAY)

(a) Disconnect the cooling fan motor connector.


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

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

A47-1 - 3 (FAN NO. 2 relay)

Always

Below 1 Ω

A47-2 - 3 (FAN NO. 3 relay)

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

A47-1 or 3 (FAN NO. 2 relay) - Body ground

Always

10 kΩ or higher

A47-2 or 3 (FAN NO. 3 relay) - Body ground

Always

10 kΩ or higher

Text in Illustration

*1

Engine Room Relay Block and Junction Block Assembly

*a

Front view of wire harness connector

(Cooling Fan Motor)

(d) Reconnect the cooling fan motor connector.

(e) Reinstall the FAN NO. 2 and FAN NO. 3 relays.


NG

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

OK
  1. INSPECT ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY (FAN NO. 1 RELAY - FAN NO. 2 RELAY)

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

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

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

Always

Below 1 Ω

Text in Illustration

*1

Engine Room Relay Block and Junction Block Assembly

(c) Reinstall the FAN NO. 1 and FAN NO. 2 relays.


NG

REPLACE ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY

OK
  1. CHECK HARNESS AND CONNECTOR (FAN NO. 2 OR NO. 3 RELAY - ECM)

(a) Remove the FAN NO. 2 and FAN NO. 3 relays from the engine room relay block and junction block assembly.


(b) Disconnect the ECM connector.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

2 (FAN NO. 2 relay) - A49-22 (FANH)

Always

Below 1 Ω

2 (FAN NO. 3 relay) - A49-21 (FANL)

Always

Below 1 Ω

Text in Illustration

*1

Engine Room Relay Block and Junction Block Assembly

*a

Front view of wire harness connector

(to ECM)

(d) Reinstall the FAN NO. 2 and FAN NO. 3 relays.

(e) Reconnect the ECM connector.


OK

REPLACE ECM


NG

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

  1. INSPECT FAN NO. 1 RELAY

(a) Inspect the FAN NO. 1 relay (See page
).


NG

REPLACE FAN NO. 1 RELAY

OK
  1. INSPECT FAN NO. 3 RELAY

(a) Inspect the FAN NO. 3 relay (See page
).


NG

REPLACE FAN NO. 3 RELAY

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

(a) Remove the FAN NO. 1, FAN NO. 2 and FAN NO. 3 relays from the engine room relay block and junction block assembly.


(b) Disconnect the ECM connector.

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

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

2 (FAN NO. 1 relay) or 2 (FAN NO. 2 relay) or A49-22 (FANH) - Body ground

Always

10 kΩ or higher

2 (FAN NO. 3 relay) or A49-21 (FANL) - Body ground

Always

10 kΩ or higher

Text in Illustration

*1

Engine Room Relay Block and Junction Block Assembly

*a

Front view of wire harness connector

(to ECM)

(d) Reinstall the FAN NO. 1, FAN NO. 2 and FAN NO. 3 relays.

(e) Reconnect the ECM connector.


OK

REPLACE ECM


NG

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

Test yourself

A quick Toyota Venza quiz: every answer comes with an explanation and a link to the manual page.