2011 INFINITI QX56 power 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-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-66
< SYSTEM DESCRIPTION >[VK56VD]
DIAGNOSIS SYSTEM (ECM)
A/F ALPHA-B1
% The mean value of the air-fuel ratio feedback cor-
rection factor per cycle is indicated.  When the engine is stopped,
a certain value is indicated.
 This data also includes the data for the air-fuel ratio
learning control.
 When engine is running, specification range is indicat-
ed in “SPEC”.
A/F ALPHA-B2
COOLAN TEMP/S
°C or °F  The engine coolant temperature (determined by
the signal voltage of the engine coolant tempera-
ture sensor) is displayed.  When the engine coolant
temperature sensor is open
or short-circuited, ECM en-
ters fail-safe mode. The en-
gine coolant temperature
determined by the ECM is
displayed.
A/F SEN1 (B1) V The A/F signal computed from the input signal of
the air fuel ratio (A/F) sensor 1 is displayed.
A/F SEN1 (B2)
HO2S2 (B1)
V The signal voltage of the heated oxygen sensor 2
is displayed.
HO2S2 (B2)
HO2S2 MNTR (B1)
RICH/LEAN Display of heated oxygen sensor 2 signal:
RICH: means the amount of oxygen after three
way catalyst is relatively small.
LEAN: means the amount of oxygen after three
way catalyst is relatively large.  When the engine is stopped,
a certain value is indicated.
HO2S2 MNTR (B2)
VHCL SPEED SE km/h or mph  The vehicle speed computed from the vehicle
speed signal sent from combination meter is dis-
played.
BATTERY VOLT V  The power supply voltage of ECM is displayed.
ACCEL SEN 1
V The accelerator pedal position sensor signal volt-
age is displayed.  ACCEL SEN 2 signal is con-
verted by ECM internally.
Thus, they differs from ECM
terminal voltage signal.
ACCEL SEN 2
TP SEN 1-B1
V The throttle position sensor signal voltage is dis-
played.  TP SEN 2-B1 signal is con-
verted by ECM internally.
Thus, they differs from ECM
terminal voltage signal.
TP SEN 2-B1
FUEL T/TMP SE
°C or °F  The fuel temperature (determined by the signal
voltage of the fuel tank temperature sensor) is dis-
played.
EVAP SYS PRES V  The signal voltage of EVAP control system pres-
sure sensor is displayed.
FUEL LEVEL SE V  The signal voltage of the fuel level sensor is dis-
played.
START SIGNAL ON/OFF  Indicates start signal status [ON/OFF] computed
by the ECM according to the signals of engine
speed and battery voltage.  After starting the engine,
[OFF] is displayed regard-
less of the starter signal.
CLSD THL POS ON/OFF  Indicates idle position [ON/OFF] computed by
ECM according to the accelerator pedal position
sensor signal.
AIR COND SIG ON/OFF  Indicates [ON/OFF] condition of the air conditioner
switch as determined by the air conditioner signal.
PW/ST SIGNAL ON/OFF  [ON/OFF] condition of the power steering system
(determined by the signal voltage of the power
steering pressure sensor signal) is indicated.
Monitored item Unit Description Remarks
Revision: 2010 May2011 QX56

ECM
EC-81
< ECU DIAGNOSIS INFORMATION > [VK56VD]
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(V) 45
(L/O) Low fuel pressure sensor Input [Engine is running]
 Warm-up condition
 Idle speed
2.4 - 3.6 V
[Engine is running]
 Warm-up condition
 Engine speed: 2,000 rpm 2.4 - 3.6 V
25
(LG) —Sensor ground
[Mass air flow sensor/ Intake air
temperature sensor] —— —
27
(P) 45
(L/O) Sensor power supply
(Power steering pressure sen-
sor/ Low fuel pressure sensor/
Electrically-controlled cooling
fan coupling)
— [Ignition switch: ON] 5 V
28
(SB) 40
(W/L) Sensor power supply
(Fuel rail pressure sensor/En-
gine oil pressure sensor)
— [Ignition switch: ON] 5 V
29
(W) 35
(—) Knock sensor (bank 1) Input [Engine is running]
 Idle speed
2.0 V*
1
31
(V/W) 40
(W/L) Fuel rail pressure sensor Input [Engine is running]
 Warm-up condition
 Idle speed
0.98 - 1.2 V
[Engine is running]
 Warm-up condition
 Revving engine from idle to 4,000 rpm quickly 1.1 - 2.9 V
32
(R) 40
(W/L) Engine coolant temperature
sensor
Input [Engine is running] 0 - 4.8 V
Output voltage varies with engine
coolant temperature.
33
(W) 35
(—) Knock sensor (bank 2) Input [Engine is running]
 Idle speed
2.0 V*
1
35
(—) —Sensor ground
(Knock sensor)
—— —
Te r m i n a l N o .
(Wire color) Description
ConditionVa l u e
(Approx.)
+ – Signal name Input/
Output
JPBIA3357ZZ
JPBIA3358ZZ
Revision: 2010 May2011 QX56

EC-82
< ECU DIAGNOSIS INFORMATION >[VK56VD]
ECM
37
(V) 175
(B) Cooling fan speed Input [Ignition switch: ON]
 Engine stopped
5 V
[Engine is running]
 Idle speed
 After warm-up condition BATTERY VOLTAGE
(11 - 14 V)
[Engine is running]
 Idle speed
 Before warm-up condition BATTERY VOLTAGE
(11 - 14 V)
39
(P/B) 45
(L/O) Power steering pressure sensor Input [Engine is running]
 Steering wheel: Being turned
0.5 - 4.5 V
[Engine is running]
 Steering wheel: Not being turned 0.4 - 0.8 V
40
(W/L) —Sensor ground
(Fuel rail pressure sensor/En-
gine coolant temperature sen-
sor/Engine oil temperature
sensor) —— —
42
(L/Y) 40
(W/L) Engine oil temperature sensor Input [Engine is running] 0 - 4.8 V
Output voltage varies with engine
oil temperature.
45
(L/O) —Sensor ground
(Power steering pressure sen-
sor/ Low fuel pressure sensor/
Electrically-controlled cooling
fan coupling) —— —
46
(SB) 175
(B) Fuel injector driver power supply Input [Ignition switch: ON]
BATTERY VOLTAGE
(11 - 14 V)
[Ignition switch: OFF] 1.5 V
47
(G) 175
(B) Heated oxygen sensor 2 heater
(bank 1)
Input[Engine is running]
 Engine speed: Below 3,600 rpm af-
ter 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 10 V
[Ignition switch: ON]
 Engine: Stopped
[Engine is running]
 Engine speed: Above 3,600 rpm BATTERY VOLTAGE
(11 - 14 V)
Te r m i n a l N o .
(Wire color) Description
ConditionVa l u e
(Approx.)
+ – Signal name Input/
Output
JPBIA3332ZZ
JPBIA3733ZZ
JMBIA0037GB
Revision: 2010 May2011 QX56