Infiniti G37 Coupe. Manual - part 582

POSITIVE CRANKCASE VENTILATION

EC-509

< COMPONENT DIAGNOSIS >

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POSITIVE CRANKCASE VENTILATION

Description

INFOID:0000000001734338

This system returns blow-by gas to the intake manifold.
The positive crankcase ventilation (PCV) valve is provided to conduct crankcase blow-by gas to the intake
manifold.
During partial throttle operation of the engine, the intake manifold sucks the blow-by gas through the PCV
valve.
Normally, the capacity of the valve is sufficient to handle any blow-by and a small amount of ventilating air.
The ventilating air is then drawn from the air inlet tubes into the crankcase. In this process the air passes
through the hose connecting air inlet tubes to rocker cover.
Under full-throttle condition, the manifold vacuum is insufficient to draw the blow-by flow through the valve.
The flow goes through the hose connection in the reverse direction.
On vehicles with an excessively high blow-by, the valve does not
meet the requirement. This is because some of the flow will go
through the hose connection to the air inlet tubes under all condi-
tions.

Component Inspection

INFOID:0000000001734339

1.

CHECK PCV VALVE

1.

PCV valve

2.

Electric throttle control actuator

3.

Mass air flow sensor

A.

Normal condition

B.

Hi-load condition

 : Fresh air

 : Blow-by air

JMBIA0858ZZ

PBIB1588E

EC-510

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POSITIVE CRANKCASE VENTILATION

With engine running at idle, remove PCV valve from rocker cover. A
properly working valve makes a hissing noise as air passes through
it. A strong vacuum should be felt immediately when a finger is
placed over valve inlet.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace PCV valve.

PBIB1589E

REFRIGERANT PRESSURE SENSOR

EC-511

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REFRIGERANT PRESSURE SENSOR

Description

INFOID:0000000001734340

The refrigerant pressure sensor is installed at the condenser of the air conditioner system. The sensor uses an
electrostatic volume pressure transducer to convert refrigerant pressure to voltage. The voltage signal is sent
to ECM, and ECM controls cooling fan system.

Component Function Check

INFOID:0000000001734341

1.

CHECK REFRIGERANT PRESSURE SENSOR FUNCTION

1.

Start engine and warm it up to normal operating temperature.

2.

Turn A/C switch and blower fan switch ON.

3.

Check the voltage between ECM harness connector and ground.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Go to 

EC-511, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000001734342

1.

CHECK GROUND CONNECTION

1.

Turn A/C switch and blower fan switch OFF.

2.

Turn ignition switch OFF.

3.

Check ground connection M95. Refer to Ground Inspection in 

GI-41, "Circuit Inspection"

.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Repair or replace ground connection.

2.

CHECK REFRIGERANT PRESSURE SENSOR POWER SUPPLY CIRCUIT

1.

Disconnect refrigerant pressure sensor harness connector.

2.

Turn ignition switch ON.

3.

Check the voltage between refrigerant pressure sensor harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> GO TO 3.

PBIB2657E

ECM

Ground

Voltage

Connector

Terminal

M107

105

(Refrigerant pressure sensor signal)

Ground

1.0 - 4.0V

Refrigerant pressure sensor

Ground

Voltage

Connector

Terminal

E77

3

Ground

Approx. 5V

EC-512

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REFRIGERANT PRESSURE SENSOR

3.

DETECT MALFUNCTIONING PART

Check the following.
• Harness connectors M6, E106
• Harness for open or short between ECM and refrigerant pressure sensor

>> Repair open circuit or short to ground or short to power in harness or connectors.

4.

CHECK REFRIGERANT PRESSURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check the continuity between refrigerant pressure sensor harness connector and ECM harness connec-
tor.

4.

Also check harness for short to ground and short to power.

Is the inspection result normal?

YES

>> GO TO 6.

NO

>> GO TO 5.

5.

DETECT MALFUNCTIONING PART

Check the following.
• Harness connectors M6, E106
• Harness for open or short between ECM and refrigerant pressure sensor

>> Repair open circuit or short to ground or short to power in harness or connectors.

6.

CHECK REFRIGERANT PRESSURE SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Check the continuity between refrigerant pressure sensor harness connector and ECM harness connec-
tor.

2.

Also check harness for short to ground and short to power.

Is the inspection result normal?

YES

>> GO TO 8.

NO

>> GO TO 7.

7.

DETECT MALFUNCTIONING PART

Check the following.
• Harness connectors M6, E106
• Harness for open or short between ECM and refrigerant pressure sensor

>> Repair open circuit or short to ground or short to power in harness or connectors.

8.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-38, "Intermittent Incident"

.

Is the inspection result normal?

YES

>> Replace refrigerant pressure sensor.

NO

>> Repair or replace. 

Refrigerant pressure sensor

ECM

Continuity

Connector

Terminal

Connector

Terminal

E77

1

M107

116

Existed

Refrigerant pressure sensor

ECM

Continuity

Connector

Terminal

Connector

Terminal

E77

2

M107

105

Existed