INFINITI QX56 2011 Factory Service Manual

COMPONENT PARTSEC-27
< SYSTEM DESCRIPTION > [VK56VD]
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The sensor detects a fuel level in the fuel tank and tr
ansmits a signal to the combination meter. The combina-
tion meter sends the fuel level sensor signal to the ECM via the CAN communication line.
It consists of two parts, one is mechanical float and the ot her is variable resistor. Fuel level sensor output volt-
age changes depending on the movement of the fuel mechanical float.
Fuel Pump Control ModuleINFOID:0000000006217674
The fuel pump control module (FPCM) controls the discharging vol-
ume of the fuel pump by transmitt ing the FPCM control signals (Low/
Mid/High) depending on driving conditions.
Fuel Rail Pressure SensorINFOID:0000000006217675
The fuel rail pressure (FRP) sensor is placed to the fuel rail and
measures fuel pressure in the fuel rail. The sensor transmits voltage
signal to the ECM. As the pressure increases, the voltage rises. The
ECM controls the fuel pressure in the fuel rail by operating high pres-
sure fuel pump. The ECM uses the signal from fuel rail pressure sen-
sor as a feedback signal.
Fuel Tank Temperature SensorINFOID:0000000006217676
The fuel tank temperature sensor is used to detect the fuel tempera-
ture inside the fuel tank. The sensor modifies a voltage signal from
the ECM. The modified signal returns to the ECM as the fuel temper-
ature input. The sensor uses a ther mistor which is sensitive to the
change in temperature. The electrical resistance of the thermistor
decreases as temperature increases.

*: These data are reference values and are measured between ECM terminals.
Heated Oxygen Sensor 2INFOID:0000000006217677
DESCRIPTION
NNBIB0006ZZ
JSBIA0291ZZ
Fuel temperature [ °C ( °F)] Voltage* (V) Resistance (k Ω)
20 (68) 3.5 2.3 - 2.7
50 (122) 2.2 0.79 - 0.90
SEF012P
Revision: 2010 May2011 QX56

EC-28
< SYSTEM DESCRIPTION >[VK56VD]
COMPONENT PARTS
The heated oxygen sensor 2, after three way catalyst (manifold),
monitors the oxygen level in the exhaust gas on each bank.
Even if switching characteristics of
the air fuel ratio (A/F) sensor 1
are shifted, the air fuel ratio is c ontrolled to stoichiometric, by the sig-
nal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates volt-
age from approximately 1 V in richer conditions to 0 V in leaner con-
ditions.
Under normal conditions the heated ox ygen sensor 2 is not used for
engine control operation.
HEATED OXYGEN SENSOR 2 HEATER
Heated oxygen sensor 2 heater is integrated in the sensor.
The ECM performs ON/OFF control of the heated oxy gen sensor 2 heater corresponding to the engine speed,
amount of intake air and engine coolant temperature.
High Pressure Fuel PumpINFOID:0000000006217678
The high pressure fuel pump is installed at the front of the engine bank 2 side and activated by the camshaft.
ECM controls the high pressure fuel pump control sol enoid valve built into the high pressure fuel pump and
adjusts the amount of discharge by changing the suction timing of the low pressure fuel.
Operating Description
SEF327R
Engine speed Heated oxygen sensor 2 heater
Above 3,600 rpm OFF
Below 3,600 rpm after the following conditions are met.
 Engine: After warming up
 Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and at idle for 1 minute under no load ON
JSBIA0285GB
Revision: 2010 May2011 QX56

COMPONENT PARTSEC-29
< SYSTEM DESCRIPTION > [VK56VD]
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Operating Chart
ICC Brake Switch & Stop Lamp SwitchINFOID:0000000006217679
Stop lamp switch and ICC brake switch are installed to brake pedal bracket.
When the brake pedal is depressed, I
CC brake switch is turned OFF and stop lamp switch is turned ON.
ECM detects the state of the brake pedal by those two types of input (ON/OFF signal).
ECM transmits ICC brake switch signal to ADAS control unit via CAN communication line.
ICC Steering SwitchINFOID:0000000006217680
ICC steering switch has variant values of electrical resistance for each button. ECM reads voltage variation of
switch, and determines which button is operated.
ECM transmits ICC steering switch signal to ADAS control unit via CAN communication line.
Ignition Coil With Power TransistorINFOID:0000000006217681
The ignition signal from the ECM is sent to and amplified by the
power transistor. The power transistor turns ON and OFF the ignition
coil primary circuit. This ON/OFF operation induces the proper high
voltage in the coil secondary circuit.
Intake Valve Timing Control Solenoid ValveINFOID:0000000006217682
Intake valve timing control solenoid valve is activated by ON/OFF
pulse duty (ratio) signals from the ECM.
The intake valve timing control solenoid valve changes the oil
amount and direction of flow through intake valve timing control unit
or stops oil flow.
The longer pulse width advances valve angle.
The shorter pulse width retards valve angle.
When ON and OFF pulse widths become equal, the solenoid valve
stops oil pressure flow to fix the intake valve angle at the control
position.
JSBIA0286GB
PBID0206J
PBIB1842E
Revision: 2010 May2011 QX56

EC-30
< SYSTEM DESCRIPTION >[VK56VD]
COMPONENT PARTS
Knock Sensor
INFOID:0000000006217683
The knock sensor is attached to t he cylinder block. It senses engine
knocking using a piezoelectric element. A knocking vibration from
the cylinder block is sensed as vibrational pressure. This pressure is
converted into a voltage signal and sent to the ECM.
Low Fuel Pressure SensorINFOID:0000000006217684
The low fuel pressure sensor is installed to low fuel pressure piping
and measures the low fuel pressu re. The sensor transmits voltage
signal to the ECM. As the pressure increases, the voltage rises.
Low Pressure Fuel PumpINFOID:0000000006217685
The low pressure fuel pump is integrated with a fuel pressure regula-
tor and a fuel filter. This pump is build into the fuel tank.
ECM controls the low pressure fuel pump via FPCM.
Malfunction Indicator Lamp (MIL)INFOID:0000000006217686
The Malfunction Indicator Lamp (MIL) is located on the combination
meter.
The MIL will illuminate when the ignition switch is turned ON without
the engine running. This is a bulb check.
When the engine is started, the MIL should turn off. If the MIL
remains illuminated, the on board diagnostic system has detected an
engine system malfunction.
For details, refer to EC-51, "
Diagnosis Description".
JSBIA0284ZZ
JSBIA0292ZZ
JPBIA3235ZZ
SEF217U
Revision: 2010 May2011 QX56

COMPONENT PARTSEC-31
< SYSTEM DESCRIPTION > [VK56VD]
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Manifold Absolute Pressure SensorINFOID:0000000006217687
The manifold absolute pressure (MAP) sensor is installed on the
intake manifold collector. Detects intake manifold pressure, and
transmits a voltage signal to the ECM.
The sensor uses a silicon diaphragm which is sensitive to the
change in pressure. As the pressu
re increases, the voltage rises.
Mass Air Flow Sensor (With Intake Air Temperature Sensor)INFOID:0000000006217688
MASS AIR FLOW SENSOR
The mass air flow (MAF) sensor (1) is placed in the stream of intake
air. It measures the intake flow ra te by measuring a part of the entire
intake flow. The mass air flow sens or controls the temperature of the
hot wire to a certain amount. The heat generated by the hot wire is
reduced as the intake air flows around it. The greater air flow, the
greater the heat loss.
Therefore, the electric current supplied to hot wire is changed to
maintain the temperature of the hot wire as air flow increases. The
ECM detects the air flow by means of this current change.
INTAKE AIR TEMPERATURE SENSOR
The intake air temperature (IAT) sensor is built-into t he mass air flow sensor. The sensor detects intake air
temperature and transmits a signal to the ECM.
The temperature sensing unit uses a thermistor which is sensitive to the change in temperature. Electrical
resistance of the thermistor decreases in response to the rise in temperature.

*: These data are reference values and are measured between ECM terminals.
Power Steering Pressure (PSP) SensorINFOID:0000000006217689
Power steering pressure (PSP) sensor is installed to the power steering high-pressure tube and detects a
power steering load.
This sensor is a potentiometer which transforms the power steering load into output voltage, and emits the
voltage signal to the ECM. The ECM controls the electric throttle control actuator and adjusts the throttle valve
opening angle to increase the engine speed and adjusts the idle speed for the increased load.
JMBIA0877ZZ
PBIA9559J
Intake air temperature
[° C ( °F)] Voltage* (V) Resistance (k
Ω)
25 (77) 3.3 1.94 - 2.06
80 (176) 1.2 0.293 - 0.349
SEF012P
Revision: 2010 May2011 QX56

EC-32
< SYSTEM DESCRIPTION >[VK56VD]
COMPONENT PARTS
Refrigerant Pressure Sensor
INFOID:0000000006217690
The refrigerant pressure sensor is installed at the c ondenser 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.
VVEL Actuator MotorINFOID:0000000006217691
The VVEL actuator motor rotates the control shaft acco rding to the control signal from the VVEL control mod-
ule. The VVEL control module judges whether the VVEL actuator motor controls the angle properly by the
VVEL control shaft position sensor signal.
VVEL Actuator Motor RelayINFOID:0000000006217692
Power supply for the VVEL actuator motor is provided to the VVEL control module via VVEL actuator motor
relay. VVEL actuator motor relay is ON/OFF controll ed by the VVEL control module. In addition, when the
VVEL actuator motor relay cannot be controlled by the VVEL control module for some reason, it ON/OFF con-
trolled by ECM.
VVEL Control ModuleINFOID:0000000006217693
The VVEL control module consists of a microcomputer and connec-
tors for signal input and output and for power supply. The VVEL con-
trol module controls VVEL system.
VVEL Control Shaft Position SensorINFOID:0000000006217694
VVEL control shaft position sensor detects the control shaft position
angle.
A magnet is installed to the tip of the control shaft.
The magnetic field changes as the control shaft rotates. This
changes output voltage of the VVEL control shaft position sensor.
VVEL control module detects the actual position angle through the
voltage change and sends the signal to ECM.
PBIB2657E
JMBIA0879ZZ
JSBIA0466ZZ
Revision: 2010 May2011 QX56

STRUCTURE AND OPERATIONEC-33
< SYSTEM DESCRIPTION > [VK56VD]
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STRUCTURE AND OPERATION
Positive Crankcase VentilationINFOID:0000000006217695
This system returns blow-by gas to the intake manifold.
The positive crankcase ventilation (PCV) valve is prov
ided to conduct crankcase blow-by gas to the intake
manifold.
During partial throttle operation of the engine, the in take 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 drawn from the air inlet tubes in to 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 in sufficient 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.
PBIB0062E
PBIB1588E
Revision: 2010 May2011 QX56

EC-34
< SYSTEM DESCRIPTION >[VK56VD]
STRUCTURE AND OPERATION
On Board Refueling V apor Recovery (ORVR)
INFOID:0000000006217696
From the beginning of refueling, the air and vapor insi de the fuel tank go through refueling EVAP vapor cut
valve and EVAP/ORVR line to the EVAP canister. The vapor is absorbed by the EVAP canister and the air is
released to the atmosphere.
When the refueling has reached the full level of the fuel tank, the refueling EVAP vapor cut valve is closed and
refueling is stopped because of auto shut-off. The vapor which was absorbed by the EVAP canister is purged
during driving.
WARNING:
When conducting inspections below, be sure to observe the following:
 Put a “CAUTION: FLAMMABLE” sign in workshop.
 Never smoke while servicing fuel system. Keep open flames and sparks away from work area.
 Always furnish the workshop with a CO
2 fire extinguisher.
CAUTION:
 Before removing fuel line parts, carry out the following procedures:
- Put drained fuel in an explosion-pr oof container and put lid on securely.
- Release fuel pressure from fuel line. Refer to EC-153, "
Work Procedure".
- Disconnect battery ground cable.
 Always replace O-ring when the fuel gauge retainer is removed.
 Never kink or twist hose and tube when they are installed.
 Never tighten hose and clamps excessively to avoid damaging hoses.
 After installation, run engine an d check for fuel leaks at connections.
 Never attempt to top off the fuel tank after the fuel pump nozzle shuts off automatically.
Continued refueling may cause fu el overflow, resulting in fuel spray and possibly a fire.
PBIB1068E
Revision: 2010 May2011 QX56

SYSTEMEC-35
< SYSTEM DESCRIPTION > [VK56VD]
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SYSTEM
ENGINE CONTROL SYSTEM
ENGINE CONTROL SYSTEM : System DiagramINFOID:0000000006217697
ENGINE CONTROL SYSTEM : System DescriptionINFOID:0000000006217698
ECM controls the engine by various functions.
JSBIA0590GB
Revision: 2010 May2011 QX56

EC-36
< SYSTEM DESCRIPTION >[VK56VD]
SYSTEM
DIRECT INJECTION GASOLINE SYSTEM
DIRECT INJECTION GASOLINE
SYSTEM : System DiagramINFOID:0000000006217699
DIRECT INJECTION GASOLINE SY STEM : System DescriptionINFOID:0000000006217700
INPUT/OUTPUT SIGNAL CHART
Function Reference
Fuel injection control EC-36, "
DIRECT INJECTION GASOLINE
SYSTEM : System De-
scription"
Fuel pressure control EC-39, "FUEL PRESSURE CONTROL : System Description"
Cooling fan controlEC-41, "COOLING FAN CONTROL : System Description"
Electric ignition controlEC-42, "ELECTRIC IGNITION SYSTEM : System Description"
Intake valve timing controlEC-43, "INTAKE VALVE TIMING CONTROL : System Description"
VVEL (Variable Valve Event & Lift) EC-44, "VVEL SYSTEM : System Description"
Evaporative emissionEC-45, "EVAPORATIVE EMISSION SYSTEM : System Descrip-
tion"
Air conditioning cut controlEC-47, "AIR CONDITIONING CUT CONT
ROL : System Descrip-
tion"
ASCD (Auto speed control device) EC-48, "AUTOMATIC SPEED CONTROL DEVICE (ASCD) : Sys-
tem Description"
Power generation voltage variable controlCHG-7, "POWER GENERATION VOLTAGE VARIABLE CON-
TROL SYSTEM : System Description"
JSBIA0471GB
Revision: 2010 May2011 QX56