Nissan Altima L32. Manual - part 239

COOLING FAN CONTROL

EC-77

< FUNCTION DIAGNOSIS >

[QR25DE FOR CALIFORNIA]

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COOLING FAN CONTROL

System Diagram

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System Description

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INPUT/OUTPUT SIGNAL CHART

*1: The ECM determines the start signal status by the signals of engine speed and battery voltage.
*2: This signal is sent to ECM through CAN communication line.

SYSTEM DESCRIPTION

ECM controls cooling fan speed corresponding to vehicle speed, engine coolant temperature, refrigerant pres-

sure, air conditioner ON signal. Then control system has 4-step control [HIGH/MID/LOW/OFF].

JMBIA0177GB

Sensor

Input signal to ECM

ECM function

Actuator

Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)

Engine speed*

1

Cooling fan 
control

IPDM E/R
↓
Cooling fan relay
↓
Cooling fan motor

Battery

Battery voltage*

1

Combination meter

Vehicle speed*

2

Engine coolant temperature sensor

Engine coolant temperature

BCM

Air conditioner ON signal*

2

Refrigerant pressure sensor

Refrigerant pressure

EC-78

< FUNCTION DIAGNOSIS >

[QR25DE FOR CALIFORNIA]

COOLING FAN CONTROL

Cooling Fan Operation

Cooling Fan Relay Operation

The ECM controls cooling fan relays through CAN communication line.

JMBIA1928GB

Cooling fan speed

Cooling fan relay

1

2

3

Stop (OFF)

OFF

OFF

OFF

Low (LOW)

ON

OFF

OFF

Middle (MID)

OFF

ON

OFF

High (HI)

OFF

ON

ON

COOLING FAN CONTROL

EC-79

< FUNCTION DIAGNOSIS >

[QR25DE FOR CALIFORNIA]

C

D

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G

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EC

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Component Parts Location

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1.

Intake valve timing control solenoid 
valve

2.

Ignition coil (with power transistor) 
and spark plug

3.

Knock sensor,
Crankshaft position sensor (POS)

4.

Air fuel ratio (A/F) sensor 1

5.

Camshaft position sensor (PHASE)

6.

Engine coolant temperature sensor

7.

Park/neutral position (PNP) switch

8.

ECM

9.

Refrigerant pressure sensor

10. Battery current sensor

11. IPDM E/R

12. Mass air flow sensor (with intake 

temperature sensor)

13. Tumble control valve actuator

14. EVAP service port

15. Electric throttle control actuator

(with built in throttle position sensor 
and throttle control motor)

16. EVAP canister purge volume control 

solenoid valve

17. Fuel injector

18. Power steering pressure sensor

ALBIA0046ZZ

EC-80

< FUNCTION DIAGNOSIS >

[QR25DE FOR CALIFORNIA]

COOLING FAN CONTROL

1.

Battery

2.

Fuel pump fuse (15A)

3.

IPDM E/R

4.

Brake master cylinder

5.

Engine ground

6.

Air cleaner assembly

7.

Mass air flow sensor (with intake air 
temperature sensor)

8.

Radiator hose (upper)

9.

Engine coolant temperature sensor

10. Intake air duct

11. Camshaft position sensor (PHASE)

12. Tie rod (RH)

13. Power steering pressure sensor

14. Knock sensor

15. Engine oil cooler

16. Crankshaft position sensor (POS)

17. Drive shaft (RH)

: Vehicle front

ALBIA0091ZZ