2011 INFINITI QX56 steering

EC-20
< SYSTEM DESCRIPTION >[VK56VD]
COMPONENT PARTS
High pressure fuel pump
EC-28, "High Pressure Fuel Pump"
Low pressure fuel pumpEC-30, "Low Pressure Fuel Pump"
Fuel pump control module (FPCM)EC-27, "Fuel Pump Control Module"
Fuel rail pressure sensorEC-27, "Fuel Rail Pressure Sensor"
Low fuel pressure sensorEC-30, "Low Fuel Pressure Sensor"
Fuel injectorEC-26, "Fuel Injector"
Fuel level sensorEC-26, "Fuel Level Sensor"
Fuel tank temperature sensorEC-27, "Fuel Tank Temperature Sensor"
A/F sensor 1
EC-21, "Air Fuel Ratio (A/F) Sensor 1"A/F sensor 1 heater
Heated oxygen sensor 2EC-27, "
Heated Oxygen Sensor 2"Heated oxygen sensor 2 heater
Manifold absolute pressure sensorEC-31, "
Manifold Absolute Pressure Sensor"
Knock sensorEC-30, "Knock Sensor"
Engine oil temperature sensorEC-25, "Engine Oil Temperature Sensor"
Power steering pressure sensorEC-31, "Power Steering Pressure (PSP) Sensor"
Electrically-controlled cooling fan coupling EC-24, "Electrically-controlled cooling fan coupling"
Intake valve timing control solenoid valveEC-29, "Intake Valve Timing Control Solenoid Valve"
VVEL control moduleEC-32, "VVEL Control Module"
VVEL actuator motor relayEC-32, "VVEL Actuator Motor Relay"
VVEL actuator motorEC-32, "VVEL Actuator Motor"
VVEL control shaft position sensor EC-32, "VVEL Control Shaft Position Sensor"
EVAP control system pressure sensor EC-26, "EVAP Control System Pressure Sensor"
EVAP canister vent control valveEC-26, "EVAP Canister Vent Control Valve"
EVAP canister purge volume control solenoid valveEC-26, "EVAP Canister Purge Volume Control Solenoid Valve"
Battery current sensor (with battery temperature sensor)EC-22, "Battery Current Sensor (With Battery Temperature Sen-
sor)"
Refrigerant pressure sensor
EC-32, "Refrigerant Pressure Sensor"
Stop lamp switch
EC-21, "ASCD Brake Switch & Stop Lamp Switch"ASCD brake switch
ASCD steering switchEC-21, "
ASCD Steering Switch"
Information displayEC-49, "AUTMATIC SPEED CONTROL DEVICE (ASCD) : Switch
Name and Function"
Stop lamp switch
EC-29, "ICC Brake Switch & Stop Lamp Switch"ICC brake switch
ICC steering switchEC-29, "
ICC Steering Switch"
Component Reference
Revision: 2010 May2011 QX56

COMPONENT PARTSEC-21
< SYSTEM DESCRIPTION > [VK56VD]
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Accelerator Pedal
Position SensorINFOID:0000000006217658
The accelerator pedal position (APP) sensor is installed on the
accelerator pedal assembly. The sensor detects the accelerator
position and sends a signal to the ECM.
Accelerator pedal position sensor has two sensors. These sensors
are a kind of potentiometer which transform the accelerator pedal
position into output voltage, and emit the voltage signals to the ECM.
The ECM judges the current opening angle of the accelerator pedal
from these signals and controls the throttle control motor based on
these signals.
Idle position of the accelerator pedal is determined by the ECM
receiving the signal from the accelerator pedal position sensor. The
ECM uses this signal for engine operations such as fuel cut.
Air Fuel Ratio (A/F) Sensor 1INFOID:0000000006217659
DESCRIPTION
The sensor element of the A/F sensor 1 is composed an electrode layer, which transports ions. It has a heater
in the element.
The sensor is capable of precise measurement = 1, but also in the lean and rich range. Together with its
control electronics, the sens or outputs a clear, continuous signal throughout a wide range.
The exhaust gas components diffuse through the diffusion layer at the sensor cell. An electrode layer is
applied voltage, and this current relative oxygen density in lean. Also this current relative hydrocarbon density
in rich.
Therefore, the A/F sensor 1 is able to indicate air fuel ratio by this
electrode layer of current. In addition, a heater is integrated in the
sensor to ensure the required operating temperature of approxi-
mately 760 °C (1,400 °F).
A/F SENSOR 1 HEATER
A/F sensor 1 heater is integrated in the sensor.
The ECM performs ON/OFF duty control of the A/F sensor 1 heater corresponding to the engine operating
condition to keep the temperature of A/F s ensor 1 element within the specified range.
ASCD Brake Switch & Stop Lamp Switch INFOID:0000000006217660
Stop lamp switch and ASCD brake switch are installed to brake pedal bracket.
When the brake pedal is depressed, ASCD 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).
ASCD Steering SwitchINFOID:0000000006217661
ASCD steering switch has variant values of electrical resistance for each button. ECM reads voltage variation
of switch, and determines which button is operated.
ASCD IndicatorsINFOID:0000000006217662
ASCD operation status is indicated by CRUISE indicator in combination meter.
ECM transmits the ASCD status signal to the combi nation meter via CAN communication according to ASCD
operation.
PBIB1741E
JSBIA0527GB
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

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

SYSTEMEC-37
< SYSTEM DESCRIPTION > [VK56VD]
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*1: This sensor is not used to control the engine system under normal conditions.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
The adoption of the direct fuel injection method enables
more accurate adjustment of fuel injection quantity by
injecting atomized high-pressure fuel directly into the cylinder. This method allows high-powered engine, low
fuel consumption, and emissions-reduction.
The amount of fuel injected from the fuel injector is determined by the ECM. The ECM controls the length of
time the valve remains open (injection pulse duration). T he amount of fuel injected is a program value in the
ECM memory. The program value is preset by engi ne operating conditions. These conditions are determined
by input signals (for engine speed and intake air and fuel rail pressure) from the crankshaft position sensor,
camshaft position sensor, mass air flow sensor and the fuel rail pressure sensor.
VARIOUS FUEL INJECTION INCREASE/DECREASE COMPENSATION
In addition, the amount of fuel injected is compens ated to improve engine performance under various operat-
ing conditions as listed below.
 During warm-up
 When starting the engine
 During acceleration
 Hot-engine operation
 When selector lever position is changed from N to D
 High-load, high-speed operation

 During deceleration
 During high engine speed operation
FUEL INJECTION CONTROL
Stratified-charge Combustion
Stratified-charge combustion is a combustion method wh ich enables extremely lean combustion by injecting
fuel in the latter half of a compression process, coll ecting combustible air-fuel around the spark plug, and form-
ing fuel-free airspace around the mixture.
Right after a start with the engine cold, the catalyst warm-up is accelerated by stratified-charge combustion.
Homogeneous Combustion
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor Engine speed*
2
Fuel injection
& mixture ratio
controlFuel injector
Camshaft position sensor Camshaft position
Mass air flow sensor Amount of intake air
Intake air temperature sensor Intake air temperature
Engine coolant temperature sensor Engine coolant temperature
Air fuel ratio (A/F) sensor 1 Density of oxygen in exhaust gas
Fuel rail pressure sensor Fuel rail pressure
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
TCM Gear position
Battery
Battery voltage*
2
Knock sensor Engine knocking condition
Power steering pressure sensor Power steering operation
Heated oxygen sensor 2*
1Density of oxygen in exhaust gas
ABS actuator and electric unit (control unit) VDC/TCS operation command
A/C auto amp. A/C ON signal
Combination meter Vehicle speed
Revision: 2010 May2011 QX56

SYSTEMEC-47
< SYSTEM DESCRIPTION > [VK56VD]
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AIR CONDITIONING CUT CONTROL : System DiagramINFOID:0000000006217713
AIR CONDITIONING CUT CONTROL : System DescriptionINFOID:0000000006217714
INPUT/OUTPUT SIGNAL CHART
*1: This signal is sent to the ECM via the CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
This system improves engine operation when the air conditioner is used.
Under the following conditions, the air conditioner is turned OFF.
 When the accelerator pedal is fully depressed.
 When cranking the engine.
 At high engine speeds.
 When the engine coolant temperature becomes excessively high.
 When operating power steering during low engine speed or low vehicle speed.
 When engine speed is excessively low.
 When refrigerant pressure is excessively low or high.
AUTOMATIC SPEED CONTROL DEVICE (ASCD)
JMBIA1457GB
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor
Camshaft position sensor Engine speed*
2
Air conditioner cut
controlIPDM E/R
↓
A/C relay
↓
Compressor
Engine coolant temperature sensor Engine coolant temperature
Accelerator pedal position sensor Accelerator pedal position
Battery
Battery voltage*
2
Refrigerant pressure sensor Refrigerant pressure
Power steering pressure sensor Power steering operation
A/C auto amp.A/C ON signal*
1
A/C evaporator temperature*1
Target A/C evaporator temperature*1
Blower fan ON signal
Combination meter Vehicle speed*
1
Revision: 2010 May2011 QX56

EC-48
< SYSTEM DESCRIPTION >[VK56VD]
SYSTEM
AUTOMATIC SPEED CONTROL DEVI CE (ASCD) : System Diagram
INFOID:0000000006217715
AUTOMATIC SPEED CONTROL DEVICE (ASCD) : System DescriptionINFOID:0000000006217716
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM via the CAN communication line
BASIC ASCD SYSTEM
 Automatic Speed Control Device (ASCD) allows a dr iver to keep vehicle at predetermined constant speed
without depressing accelerator pedal. Driver can be set the vehicle speed in the set speed range.
 ECM controls throttle angle of electric th rottle control actuator to regulate engine speed.
 Operation status of ASCD is indicated in combination meter.
 If any malfunction occurs in the ASCD system, it automatically deactivates the ASCD control.
Refer to EC-49, "
AUTMATIC SPEED CONTROL DEVICE (A SCD) : Switch Name and Function" for ASCD
operating instructions.
CAUTION:
Always drive vehicle in a safe manner according to traffic conditions and obey all traffic laws.
CAN COMMUNICATION
CAN COMMUNICATION : System DescriptionINFOID:0000000006217718
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication s peed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CA N communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only.
Refer to LAN-28, "
CAN COMMUNICATION SYSTEM : CAN Communication Signal Chart", about CAN com-
munication for detail.
JPBIA3272GB
Sensor Input signal to ECM ECM function Actuator
ASCD steering switch ASCD steering switch operation
ASCD vehicle speed control Electric throttle control ac-
tuator
 Combination meter
ASCD brake switch
Brake pedal operation
Sto p l am p s w it ch
TCM Park/neutral position signal
Output shaft revolution signal*
Combination meter Vehicle speed signal*
Revision: 2010 May2011 QX56

OPERATIONEC-49
< SYSTEM DESCRIPTION > [VK56VD]
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OPERATION
AUTMATIC SPEED CONTROL DEVICE (ASCD)
AUTMATIC SPEED CONTROL DEVICE (A
SCD) : Switch Name and Function
INFOID:0000000006217719
SWITCHES AND INDICATORS
SET SPEED RANGE
ASCD system can be set the following vehicle speed.
SWITCH OPERATION
CANCEL CONDITION
 When any of following conditions exist, the cruise operation is canceled.
- CANCEL switch is pressed
- ASCD MAIN switch pressed (Set speed is cleared)
- More than two switches at ASCD steering switch ar e pressed at the same time (Set speed is cleared)
- Brake pedal is depressed
- Selector lever position is changed to N, P or R
- Vehicle speed decreased to 13 km/h (8 MPH) lower than the set speed
- TCS system is operated
 When the ECM detects any of the following conditions , the ECM cancels the cruise operation and informs
the driver by blinking CRUISE indicator lamp.
1. CRUISE indicator lamp 2. CANCEL switch 3. ASCD MAIN switch
4. SET/COAST switch 5. RESUME/ACCELERATE switch
A. On the combination meter B. On the steering wheel
JPBIA3226ZZ
Minimum speed (Approx.) Maximum speed (Approx.)
40 km/h (25 MPH) 143 km/h (88 MPH)
Item Function
CANCEL switch Cancels the cruise control driving.
RESUME/ACCELERATE switch  Resumes the set speed.
 Increases speed incrementally during cruise control driving.
SET/COAST switch  Sets desired cruise speed.
 Decreases speed incrementally during cruise control driving.
ASCD MAIN switch Master switch to activate the ASCD system.
(CRUISE indicator lamp is turn
ed ON when ASCD system is ON.)
Revision: 2010 May2011 QX56