2006 INFINITI QX56 air condition

EC-1
ENGINE CONTROL SYSTEM
B ENGINE
CONTENTS
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Revision: November 2009 2006 QX56
INDEX FOR DTC ...................................................
..... 8
DTC No. Index .................................................... ..... 8
Alphabetical Index ............................................... ... 12
PRECAUTIONS ..................................................... ... 16
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” ............................................................. ... 16
On Board Diagnostic (OBD) System of Engine and
A/T ....................................................................... ... 16
Precaution ........................................................... ... 16
PREPARATION ...................................................... ... 20
Special Service Tools .......................................... ... 20
Commercial Service Tools ................................... ... 22
ENGINE CONTROL SYSTEM ............................... ... 23
System Diagram .................................................. ... 23
Multiport Fuel Injection (MFI) System ................. ... 24
Electronic Ignition (EI) System ............................ ... 26
Fuel Cut Control (at No Load and High Engine
Speed) ................................................................. ... 27
AIR CONDITIONING CUT CONTROL .................. ... 28
Input/Output Signal Chart .................................... ... 28
System Description ............................................. ... 28
AUTOMATIC SPEED CONTROL DEVICE (ASCD) ... 29
System Description ............................................. ... 29
Component Description ....................................... ... 30
CAN COMMUNICATION ....................................... ... 31
System Description ............................................. ... 31
EVAPORATIVE EMISSION SYSTEM .................... ... 32
Description .......................................................... ... 32
Component Inspection ........................................ ... 35
Removal and Installation ..................................... ... 36
How to Detect Fuel Vapor Leakage .................... ... 37
ON BOARD REFUELING VAPOR RECOVERY
(ORVR) ................................................................... ... 39
System Description ............................................. ... 39
Diagnostic Procedure .......................................... ... 40
Component Inspection ........................................ ... 43
POSITIVE CRANKCASE VENTILATION .............. ... 45
Description .......................................................... ... 45
Component Inspection ........................................ ... 45IVIS (INFINITI VEHICLE IMMOBILIZER SYSTEM-
NATS) .....................................................................
... 47
Description ........................................................... ... 47
ON BOARD DIAGNOSTIC (OBD) SYSTEM ......... ... 48
Introduction .......................................................... ... 48
Two Trip Detection Logic ..................................... ... 48
Emission-related Diagnostic Information ............. ... 49
Malfunction Indicator Lamp (MIL) ........................ ... 63
OBD System Operation Chart ............................. ... 65
BASIC SERVICE PROCEDURE ............................ ... 71
Basic Inspection ..................................................... 71
Idle Speed and Ignition Timing Check ................. ... 76
VIN Registration ..................................................... 77
Accelerator Pedal Released Position Learning ... ... 78
Throttle Valve Closed Position Learning .............. ... 78
Idle Air Volume Learning ..................................... ... 78
Fuel Pressure Check .............................................. 80
TROUBLE DIAGNOSIS ......................................... ... 83
Trouble Diagnosis Introduction ............................ ... 83
DTC Inspection Priority Chart .............................. ... 89
Fail-safe Chart ..................................................... ... 91
Symptom Matrix Chart ......................................... ... 92
Engine Control Component Parts Location ......... ... 96
Vacuum Hose Drawing ........................................ .102
Circuit Diagram .................................................... .103
ECM Harness Connector Terminal Layout .......... .105
ECM Terminals and Reference Value .................. .105
CONSULT-II Function (ENGINE) ......................... .114
Generic Scan Tool (GST) Function ...................... .127
CONSULT-II Reference Value in Data Monitor .... .129
Major Sensor Reference Graph in Data Monitor
Mode .................................................................... .132
TROUBLE DIAGNOSIS - SPECIFICATION VALUE .134
Description ........................................................... .134
Testing Condition ................................................. .134
Inspection Procedure ........................................... .134
Diagnostic Procedure .......................................... .135
TROUBLE DIAGNOSIS FOR INTERMITTENT INCI-
DENT ...................................................................... .144

EC-24Revision: November 2009
ENGINE CONTROL SYSTEM
2006 QX56
Multiport Fuel Injection (MFI) SystemUBS00KZ7
INPUT/OUTPUT SIGNAL CHART
*1: This sensor is not used to control the engine system. This is used only for the on board diagnosis.
*2: This signal is sent to the ECM through CAN communication line.
*3: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
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). The amount of fuel injected is a program value in the
ECM memory. The program value is preset by engine operating conditions. These conditions are determined
by input signals (for engine speed and intake air) from both the crankshaft position sensor and the mass air
flow sensor.
VARIOUS FUEL INJECTION INCREASE/DECREASE COMPENSATION
In addition, the amount of fuel injected is compensated 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 is changed from N to D

High-load, high-speed operation


During deceleration

During high engine speed operation
Sensor Input signal to ECMECM functionActuator
Crankshaft position sensor (POS) Engine speed*
3
Piston position
Fuel injection
& mixture ratio
controlFuel injector
Camshaft position sensor (PHASE)
Mass air flow sensor
Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Air fuel ratio (A/F) sensor 1 Density of oxygen in exhaust gas
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Park/neutral position (PNP) switch Gear position
Knock sensor Engine knocking condition
Battery Battery voltage*
3
Power steering pressure sensorPower steering operation
Heated oxygen sensor 2 Density of oxygen in exhaust gas*
1
ABS actuator and electric unit (control unit)VDC/TCS operation command*2
Air conditioner switch
Air conditioner operation*2
Wheel sensorVehicle speed*2

ENGINE CONTROL SYSTEMEC-25
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MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system provides the best air-fuel mixture ratio for driveability and emission control.
The three way catalyst (manifold) can then better reduce CO, HC and NOx emissions. This system uses air
fuel ratio (A/F) sensor 1 in the exhaust manifold to monitor whether the engine operation is rich or lean. The
ECM adjusts the injection pulse width according to the sensor voltage signal. For more information about air
fuel ratio (A/F) sensor 1, refer to EC-213, "
DTC P0130, P0150 A/F SENSOR 1" . This maintains the mixture
ratio within the range of stoichiometric (ideal air-fuel mixture).
This stage is referred to as the closed loop control condition.
Heated oxygen sensor 2 is located downstream of the three way catalyst (manifold). Even if the switching
characteristics of air fuel ratio (A/F) sensor 1 shift, the air-fuel ratio is controlled to stoichiometric by the signal
from heated oxygen sensor 2.
Open Loop Control
The open loop system condition refers to when the ECM detects any of the following conditions. Feedback
control stops in order to maintain stabilized fuel combustion.

Deceleration and acceleration

High-load, high-speed operation

Malfunction of A/F sensor 1 or its circuit

Insufficient activation of A/F sensor 1 at low engine coolant temperature

High engine coolant temperature

During warm-up

After shifting from N to D

When starting the engine
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors the mixture ratio signal transmitted from A/F sensor 1.
This feedback signal is then sent to the ECM. The ECM controls the basic mixture ratio as close to the theoret-
ical mixture ratio as possible. However, the basic mixture ratio is not necessarily controlled as originally
designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic changes dur-
ing operation (i.e., injector clogging) directly affect mixture ratio.
Accordingly, the difference between the basic and theoretical mixture ratios is monitored in this system. This is
then computed in terms of “injection pulse duration” to automatically compensate for the difference between
the two ratios.
“Fuel trim ” refers to the feedback compensation value compared against the basic injection duration. Fuel trim
includes short term fuel trim and long term fuel trim.
“Short term fuel trim ” is the short-term fuel compensation used to maintain the mixture ratio at its theoretical
value. The signal from A/F sensor 1 indicates whether the mixture ratio is RICH or LEAN compared to the the-
oretical value. The signal then triggers a reduction in fuel volume if the mixture ratio is rich, and an increase in
fuel volume if it is lean.
“Long term fuel trim ” is overall fuel compensation carried out long-term to compensate for continual deviation
of the short term fuel trim from the central value. Such deviation will occur due to individual engine differences,
wear over time and changes in the usage environment.
PBIB3020E

EC-26Revision: November 2009
ENGINE CONTROL SYSTEM
2006 QX56
FUEL INJECTION TIMING
Two types of systems are used.
Sequential Multiport Fuel Injection System
Fuel is injected into each cylinder during each engine cycle according to the firing order. This system is used
when the engine is running.
Simultaneous Multiport Fuel Injection System
Fuel is injected simultaneously into all eight cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The eight fuel injectors will then receive the signals two times for each engine cycle.
This system is used when the engine is being started and/or if the fail-safe system (CPU) is operating.
FUEL SHUT-OFF
Fuel to each cylinder is cut off during deceleration, operation of the engine at excessively high speeds or oper-
ation of the vehicle at excessively high speed.
Electronic Ignition (EI) SystemUBS00KZ8
INPUT/OUTPUT SIGNAL CHART
*1: This signal is sent to the ECM through CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
Firing order: 1 - 8 - 7 - 3 - 6 - 5 - 4 -2
The ignition timing is controlled by the ECM to maintain the best air-fuel ratio for every running condition of the
engine. The ignition timing data is stored in the ECM.
The ECM receives information such as the injection pulse width and camshaft position sensor signal. Comput-
ing this information, ignition signals are transmitted to the power transistor.
During the following conditions, the ignition timing is revised by the ECM according to the other data stored in
the ECM.

At starting

During warm-up

At idle

At low battery voltage
PBIB0122E
SensorInput signal to ECMECM functionActuator
Crankshaft position sensor (POS) Engine speed*
2
Piston position
Ignition timing
controlPower transistor
Camshaft position sensor (PHASE)
Mass air flow sensor
Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Knock sensor Engine knocking
Park/neutral position (PNP) switch Gear position
Battery Battery voltage*
2
Wheel sensorVehicle speed*1

EC-28Revision: November 2009
AIR CONDITIONING CUT CONTROL
2006 QX56
AIR CONDITIONING CUT CONTROLPFP:23710
Input/Output Signal ChartUBS00KZA
*1: This signal is sent to the ECM through CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
System DescriptionUBS00KZB
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.
SensorInput Signal to ECMECM functionActuator
Air conditioner switch Air conditioner ON signal*
1
Air conditioner
cut controlAir conditioner relay
Accelerator pedal position sensor
Accelerator pedal position
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE) Engine speed*
2
Engine coolant temperature sensor
Engine coolant temperature
Battery Battery voltage*
2
Refrigerant pressure sensorRefrigerant pressure
Power steering pressure sensor Power steering operation
Wheel sensor Vehicle speed*
1

POSITIVE CRANKCASE VENTILATIONEC-45
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POSITIVE CRANKCASE VENTILATIONPFP:11810
DescriptionUBS00KZM
SYSTEM DESCRIPTION
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 venti-
lating 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 InspectionUBS00KZN
PCV (POSITIVE CRANKCASE VENTILATION) VALVE
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.
PBIB0062E
PBIB1588E
PBIB1589E

ON BOARD DIAGNOSTIC (OBD) SYSTEMEC-49
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Revision: November 2009 2006 QX56
Therefore, when electrical controlled throttle and part of ECM related diagnoses are continuously detected as
NG for 5 trips, ECM warns the driver that engine control system malfunctions and MIL circuit is open by means
of operating fail-safe function.
The fail-safe function also operates when above diagnoses except MIL circuit are detected and demands the
driver to repair the malfunction.
Emission-related Diagnostic InformationUBS00KZR
EMISSION-RELATED DIAGNOSTIC INFORMATION ITEMS
×:Applicable —: Not applicable
Engine operating condition in fail-safe mode
Engine speed will not rise more than 2,500 rpm due to the fuel cut
Items
(CONSULT-II screen terms) DTC*
1
SRT code
Test value/
Te s t l i m i t
(GST only) Trip MIL
Refer-
ence page
CONSULT-II
GST*
2ECM*3
CAN COMM CIRCUIT U1000
1000*5—— 1×EC-151
CAN COMM CIRCUIT U1001
1001*5—— 2—EC-151
CONTROL UNIT(CAN) U1010 1010——1×EC-154
NO DTC IS DETECTED.
FURTHER TESTING
MAY BE REQUIRED. P0000 0000
———
Flashing*7EC-64
A/F SEN1 HTR (B1) P0031 0031—×2×EC-156
A/F SEN1 HTR (B1) P0032 0032—×2×EC-156
HO2S2 HTR (B1) P0037 0037—×2×EC-163
HO2S2 HTR (B1) P0038 0038—×2×EC-163
A/F SEN1 HTR (B2) P0051 0051—×2×EC-156
A/F SEN1 HTR (B2) P0052 0052—×2×EC-156
HO2S2 HTR (B2) P0057 0057—×2×EC-163
HO2S2 HTR (B2) P0058 0058—×2×EC-163
MAF SEN/CIRCUIT P0101 0101——2×EC-171
MAF SEN/CIRCUIT P0102 0102——1×EC-180
MAF SEN/CIRCUIT P0103 0103——1×EC-180
IAT SEN/CIRCUIT P0112 0112——2×EC-188
IAT SEN/CIRCUIT P0113 0113——2×EC-188
ECT SEN/CIRC P0117 0117——1×EC-192
ECT SEN/CIRC P0118 0118——1×EC-192
TP SEN 2/CIRC P0122 0122——1×EC-198
TP SEN 2/CIRC P0123 0123——1×EC-198
ECT SENSOR P0125 0125——2×EC-205
IAT SENSOR P0127 0127——2×EC-208
THERMSTAT FNCTN P0128 0128——2×EC-211
A/F SENSOR1 (B1) P0130 0130—×2×EC-213
A/F SENSOR1 (B1) P0131 0131—×2×EC-223
A/F SENSOR1 (B1) P0132 0132—×2×EC-232
A/F SENSOR1 (B1) P0133 0133××2 ×EC-241
HO2S2 (B1) P0137 0137××2 ×EC-253
HO2S2 (B1) P0138 0138××2 ×EC-264
HO2S2 (B1) P0139 0139××2 ×EC-277
A/F SENSOR1 (B2) P0150 0150—×2×EC-213
A/F SENSOR1 (B2) P0151 0151—×2×EC-223

ON BOARD DIAGNOSTIC (OBD) SYSTEMEC-53
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Revision: November 2009 2006 QX56
If a malfunction is detected during the 1st trip, the 1st trip DTC is stored in the ECM memory. The MIL will not
light up (two trip detection logic). If the same malfunction is not detected in the 2nd trip (meeting the required
driving pattern), the 1st trip DTC is cleared from the ECM memory. If the same malfunction is detected in the
2nd trip, both the 1st trip DTC and DTC are stored in the ECM memory and the MIL lights up. In other words,
the DTC is stored in the ECM memory and the MIL lights up when the same malfunction occurs in two consec-
utive trips. If a 1st trip DTC is stored and a non-diagnostic operation is performed between the 1st and 2nd
trips, only the 1st trip DTC will continue to be stored. For malfunctions that blink or light up the MIL during the
1st trip, the DTC and 1st trip DTC are stored in the ECM memory.
Procedures for clearing the DTC and the 1st trip DTC from the ECM memory are described in EC-61, "
HOW
TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION" .
For malfunctions in which 1st trip DTCs are displayed, refer to EC-49, "
EMISSION-RELATED DIAGNOSTIC
INFORMATION ITEMS" . These items are required by legal regulations to continuously monitor the system/
component. In addition, the items monitored non-continuously are also displayed on CONSULT-II.
1st trip DTC is specified in Service $07 of SAE J1979. 1st trip DTC detection occurs without lighting up the MIL
and therefore does not warn the driver of a malfunction. However, 1st trip DTC detection will not prevent the
vehicle from being tested, for example during Inspection/Maintenance (I/M) tests.
When a 1st trip DTC is detected, check, print out or write down and erase (1st trip) DTC and Freeze Frame
data as specified in Work Flow procedure Step 2, refer to EC-84, "
WORK FLOW" . Then perform DTC Confir-
mation Procedure or Overall Function Check to try to duplicate the malfunction. If the malfunction is dupli-
cated, the item requires repair.
How to Read DTC and 1st Trip DTC
DTC and 1st trip DTC can be read by the following methods.
With CONSULT-II
With GST
CONSULT-II or GST (Generic Scan Tool) Examples: P0340, P0850, P1148, etc.
These DTCs are prescribed by SAE J2012.
(CONSULT-II also displays the malfunctioning component or system.)
No Tools
The number of blinks of the MIL in the Diagnostic Test Mode II (Self-Diagnostic Results) indicates the DTC.
Example: 0340, 0850, 1148, etc.
These DTCs are controlled by NISSAN.

1st trip DTC No. is the same as DTC No.

Output of a DTC indicates a malfunction. However, GST or the Diagnostic Test Mode II do not indi-
cate whether the malfunction is still occurring or has occurred in the past and has returned to nor-
mal. CONSULT-II can identify malfunction status as shown below. Therefore, using CONSULT-II (if
available) is recommended.
A sample of CONSULT-II display for DTC and 1st trip DTC is shown below. DTC or 1st trip DTC of a malfunc-
tion is displayed in SELF-DIAGNOSTIC RESULTS mode of CONSULT-II. Time data indicates how many times
the vehicle was driven after the last detection of a DTC.
If the DTC is being detected currently, the time data will be [0].
If a 1st trip DTC is stored in the ECM, the time data will be [1t].
FREEZE FRAME DATA AND 1ST TRIP FREEZE FRAME DATA
The ECM records the driving conditions such as fuel system status, calculated load value, engine coolant tem-
perature, short term fuel trim, long term fuel trim, engine speed, vehicle speed, absolute throttle position, base
fuel schedule and intake air temperature at the moment a malfunction is detected.
Data which are stored in the ECM memory, along with the 1st trip DTC, are called 1st trip freeze frame data.
The data, stored together with the DTC data, are called freeze frame data and displayed on CONSULT-II or
PBIB0911E