2011 INFINITI QX56 wheel

P1574 ICC VEHICLE SPEED SENSOR
EC-449
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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P1574 ICC VEHICLE SPEED SENSOR
DescriptionINFOID:0000000006288352
The ECM receives two vehicle speed signals by the CAN
communication line. One is sent from “combination
meter”, and the other is from TCM (Transmission cont rol module). The ECM uses these signals for ICC con-
trol. Refer to CCS-12, "
System Description" for ICC functions.
DTC LogicINFOID:0000000006288353
DTC DETECTION LOGIC
NOTE:
If DTC P1574 is displayed with DTC UXXXX, first perform the tr ouble diagnosis for DTC UXXXX.
 If DTC P1574 is displayed with DT C P0500, first perform the trouble diagnosis for DTC P0500. Refer
to EC-356, "
DTC Logic".
 If DTC P1574 is displayed with DT C P0605, first perform the trouble diagnosis for DTC P0605. Refer
to EC-376, "
DTC Logic".
 If DTC P1574 is displayed with DT C P0607, first perform the trouble diagnosis for DTC P0607. Refer
to EC-378, "
DTC Logic".
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Start engine (VDC switch OFF).
2. Drive the vehicle at more than 40 km/h (25 MPH). CAUTION:
Always drive vehicle at a safe speed.
NOTE:
This procedure may be conducted with the drive wheel s lifted in the shop or by driving the vehicle.
If a road test is expected to be easier , it is unnecessary to lift the vehicle.
3. Check DTC.
Is DTC detected?
YES >> Proceed to EC-449, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006288354
1.CHECK DTC WITH TCM
Check DTC with TCM. Refer to TM-61, "
CONSULT-III Function (TRANSMISSION)".
Is the inspection result normal?
YES >> GO TO 2.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1574 ASCD VHL SPD SEN
(ICC vehicle speed sensor) ECM detects a difference between two vehicle
speed signals is out of the specified range.  Harness or connectors
(The CAN communication line is open or
shorted.)
 Combination meter
 ABS actuator and electric unit (control unit)
 Wheel sensor
TCM
ECM
Revision: 2010 May2011 QX56

EC-538
< SERVICE DATA AND SPECIFICATIONS (SDS) [VK56VD]
SERVICE DATA AND SPECIFICATIONS (SDS)
SERVICE DATA AND SPECIFICATIONS (SDS)
SERVICE DATA AND SPECIFICATIONS (SDS)
Idle SpeedINFOID:0000000006218038
*: Under the following conditions
 A/C switch: OFF
 Electric load: OFF (Lights, heater fan & rear window defogger)
 Steering wheel: Kept in straight-ahead position
Ignition TimingINFOID:0000000006218039
*: Under the following conditions
 A/C switch: OFF
 Electric load: OFF (Lights, heater fan & rear window defogger)
 Steering wheel: Kept in straight-ahead position
Calculated Load ValueINFOID:0000000006218040
Mass Air Flow SensorINFOID:0000000006218041
*: Engine is warmed up to normal operating temperature and running under no load.Condition Specification
No load* (in P or N position) 600 ± 50 rpm
Condition Specification
No load* (in P or N position) 12 ± 2 °BTDC
Condition Specification (U sing CONSULT-III or GST)
At idle 5 – 35%
At 2,500 rpm 5 – 35%
Supply voltageBattery voltage (11 – 14 V)
Output voltage at idle 0.9 – 1.1 V*
Mass air flow (Using CONSULT-III or GST) 1.0 – 5.0 g/s at idle*
7.0 – 20.0 g/s at 2,500 rpm*
Revision: 2010 May2011 QX56

EM-1
ENGINE
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SECTION EM
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CONTENTS
ENGINE MECHANICAL
PRECAUTION ................ ...............................3
PRECAUTIONS .............................................. .....3
Precaution for Procedure without Cowl Top Cover ......3
Precaution for Supplemental Restraint System
(SRS) "AIR BAG" and "SEAT BELT PRE-TEN-
SIONER" ...................................................................
3
Precaution Necessary for Steering Wheel Rota-
tion after Battery Disconnect .....................................
3
Precaution for Drain Engine Coolant and Engine
Oil ..............................................................................
4
Precaution for Disconnecting Fuel Piping .................4
Precaution for Handling High Pressure Fuel Sys-
tem ............................................................................
4
Precaution for Removal and Disassembly ................4
Precaution for Inspection, Repair and Replace-
ment ..........................................................................
4
Precaution for Assembly and Installation ..................4
Parts Requiring Angle Tightening .............................5
Precaution for Liquid Gasket .....................................5
Definitions of Bank Names ........................................6
PREPARATION ............................................7
PREPARATION .............................................. .....7
Special Service Tool ........................................... ......7
Commercial Service Tool ..........................................9
BASIC INSPECTION ...................................12
CAMSHAFT VALVE CLEARANCE ............... ....12
Inspection ............................................................ ....12
COMPRESSION PRESSURE ............................16
Inspection ............................................................ ....16
SYMPTOM DIAGNOSIS ..............................18
NOISE, VIBRATION AND HARSHNESS
(NVH) TROUBLESHOOTING ........................ ....
18
NVH Troubleshooting - Engine Noise .............. ....18
Use the Chart Below to Help You Find the C
ause of the Symptom ........................................ ....
19
PERIODIC MAINTENANCE ........................20
DRIVE BELTS ...................................................20
Exploded View ..................................................... ....20
Checking ..................................................................20
Tension Adjustment ................................................20
Removal and Installation .........................................20
Inspection ................................................................21
AIR CLEANER FILTER .....................................22
Exploded View .........................................................22
Removal and Installation .........................................22
SPARK PLUG ...................................................23
Exploded View .........................................................23
Removal and Installation .........................................23
Inspection ................................................................24
REMOVAL AND INSTALLATION ...............25
ENGINE COVER ...............................................25
Exploded View ..................................................... ....25
Removal and Installation .........................................25
DRIVE BELT AUTO TENSIONER AND IDLER
PULLEY .............................................................
26
Exploded View .........................................................26
Removal and Installation .........................................26
AIR CLEANER AND AIR DUCT .......................27
Exploded View .........................................................27
Removal and Installation .........................................27
Inspection ................................................................28
IGNITION COIL .................................................29
Exploded View .........................................................29
Removal and Installation .........................................29
INTAKE MANIFOLD .........................................30
Exploded View .........................................................30
Revision: 2010 May2011 QX56

PRECAUTIONSEM-3
< PRECAUTION >
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PRECAUTION
PRECAUTIONS
Precaution for Procedur
e without Cowl Top CoverINFOID:0000000006289506
When performing the procedure after removing cowl top cover, cover
the lower end of windshield with urethane, etc.
Precaution for Supplemental Restraint System (SRS) "AIR BAG" and "SEAT BELT
PRE-TENSIONER"
INFOID:0000000006417202
The Supplemental Restraint System such as “A IR BAG” and “SEAT BELT PRE-TENSIONER”, used along
with a front seat belt, helps to reduce the risk or severi ty of injury to the driver and front passenger for certain
types of collision. This system includes seat belt switch inputs and dual stage front air bag modules. The SRS
system uses the seat belt switches to determine the front air bag deployment, and may only deploy one front
air bag, depending on the severity of a collision and whether the front occupants are belted or unbelted.
Information necessary to service the system safely is included in the “SRS AIR BAG” and “SEAT BELT” of this
Service Manual.
WARNING:
• To avoid rendering the SRS inoper ative, which could increase the risk of personal injury or death in
the event of a collision that would result in air ba g inflation, all maintenance must be performed by
an authorized NISSAN/INFINITI dealer.
 Improper maintenance, including in correct removal and installation of the SRS, can lead to personal
injury caused by unintentional act ivation of the system. For removal of Spiral Cable and Air Bag
Module, see the “SRS AIR BAG”.
 Do not use electrical test equipm ent on any circuit related to the SRS unless instructed to in this
Service Manual. SRS wiring harnesses can be identi fied by yellow and/or orange harnesses or har-
ness connectors.
PRECAUTIONS WHEN USING POWER TOOLS (AIR OR ELECTRIC) AND HAMMERS
WARNING:
 When working near the Air Bag Diagnosis Sensor Unit or other Air Bag System sensors with the
ignition ON or engine running, DO NOT use air or electric power tools or strike near the sensor(s)
with a hammer. Heavy vibration could activate the sensor(s) and deploy the air bag(s), possibly
causing serious injury.
 When using air or electric power tools or hammers , always switch the ignition OFF, disconnect the
battery, and wait at least 3 minutes before performing any service.
Precaution Necessary for Steering Wh eel Rotation after Battery Disconnect
INFOID:0000000006289508
NOTE:
 Before removing and installing any control units, first tu rn the push-button ignition switch to the LOCK posi-
tion, then disconnect both battery cables.
 After finishing work, confirm that all control unit connectors are connected properly, then re-connect both
battery cables.
 Always use CONSULT-III to perform self-diagnosis as a part of each function inspection after finishing work.
If a DTC is detected, perform trouble diagnos is according to self-diagnosis results.
For vehicle with steering lock unit, if the battery is disconnected or discharged, the steering wheel will lock and
cannot be turned.
PIIB3706J
Revision: 2010 May2011 QX56

EM-4
< PRECAUTION >
PRECAUTIONS
If turning the steering wheel is required with the battery disconnected or discharged, follow the operation pro-
cedure below before starting the repair operation.
OPERATION PROCEDURE
1. Connect both battery cables.
NOTE:
Supply power using jumper cables if battery is discharged.
2. Turn the push-button ignition switch to ACC position. (At this time, the steering lock will be released.)
3. Disconnect both battery cables. The steering lock wi ll remain released with both battery cables discon-
nected and the steering wheel can be turned.
4. Perform the necessary repair operation.
5. When the repair work is completed, re-connect bot h battery cables. With the brake pedal released, turn
the push-button ignition switch from ACC position to ON position, then to LOCK position. (The steering
wheel will lock when the push-button igniti on switch is turned to LOCK position.)
6. Perform self-diagnosis check of all control units using CONSULT-III.
Precaution for Drain Engine Coolant and Engine OilINFOID:0000000006289509
Drain engine coolant and engine oil when engine is cooled.
Precaution for Disconnecting Fuel PipingINFOID:0000000006289510
 Before starting work, check no fire or sp ark producing items are in the work area.
 Release fuel pressure before disconnecting and disassembly.
 After disconnecting pipes, plug openings to stop fuel leakage.
Precaution for Handling High Pressure Fuel SystemINFOID:0000000006289511
 High pressure fuel system components are betw een high pressure fuel pump and fuel injector.
 Always release fuel pressure and never start the engine when performing removal and installation.
 When removing or installing parts without releasing fuel pressure, fuel may be splashed and, if fuel contacts
skin or eyes, it may cause inflammation.
Precaution for Removal and DisassemblyINFOID:0000000006289512
 When instructed to use SST, use specified tools. Always be careful to work safely, avoid forceful or unin-
structed operations.
 Exercise maximum care to avoid damage to mating or sliding surfaces.
 Cover openings of engine system with tape or the equival ent, if necessary, to seal out foreign materials.
 Mark and arrange disassembly parts in an organi zed way for easy troubleshooting and assembly.
 When loosening nuts and bolts, as a basic rule, star t with the one furthest outside, then the one diagonally
opposite, and so on. If the order of loosening is specified, do exactly as specified. Power tools may be used
where noted in the step.
Precaution for Inspection, Repair and ReplacementINFOID:0000000006289513
Before repairing or replacing, thoroughly inspect parts. Inspect new replacement parts in the same way, and
replace if necessary.
Precaution for Assembly and InstallationINFOID:0000000006289514
 Use torque wrench to tighten bolts or nuts to specification.
 When tightening nuts and bolts, as a basic rule, equally tighten in several different steps starting with the
ones in center, then ones on inside and outside diagonally in this order. If the order of tightening is specified,
do exactly as specified.
 Replace with new gasket, packing, oil seal or O-ring.
 Thoroughly wash, clean, and air-blow each part. Carefully check engine oil or engine coolant passages for
any restriction and blockage.
 Dowel pins are used for several parts alignment. When replacing and reassembling parts with dowel pins,
check that dowel pins are installed in the original position.
Revision: 2010 May2011 QX56

AIR CLEANER AND AIR DUCTEM-27
< REMOVAL AND INSTALLATION >
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AIR CLEANER AND AIR DUCT
Exploded ViewINFOID:0000000006289538
Removal and InstallationINFOID:0000000006289539
REMOVAL
NOTE:
Mass air flow sensor is removable under the car-mounted condition.
1. Remove engine cover. Refer to
EM-25, "
Exploded View".
2. Disconnect mass air flow sensor harness connector.
3. Remove air cleaner case and mass air flow sensor assembly and air duct by disconnecting their joints.
 Add matching marks, if necessary for easier installation.
4. Remove mass air flow sensor from air cleaner case, if necessary. CAUTION:
Handle mass air flow sensor accordi ng to the following instructions.
 Never impact it.
 Never disassemble it.
 Never touch its sensor.
5. Disconnect PCV hose from air duct.
6. Remove air duct.
7. Remove air cleaner filter.
8. Remove air cleaner case (lower).
9. Remove adapter.
10. If remove resonator (location in wheel house), refer to following.
a. Remove LH front wheel and tire.
b. Remove fender protector. Refer to EXT-23, "
FENDER PROTECTOR : Exploded View".
c. Remove resonator.
INSTALLATION
1. Resonator 2. Adapter 3. Air cleaner case (lower)
4. Air cleaner filter 5. Air cleaner case (upper) 6. Mass air flow sensor
7. Air duct 8. Clamp
Vehicle front
Refer to GI-4, "
Components" for symbols in the figure.
JPBIA3260GB
Revision: 2010 May2011 QX56

EM-40
< REMOVAL AND INSTALLATION >
EXHAUST MANIFOLD AND THREE WAY CATALYST
EXHAUST MANIFOLD AND THREE WAY CATALYST
Exploded ViewINFOID:0000000006289550
Removal and InstallationINFOID:0000000006289551
REMOVAL
WARNING:
Perform the work when the exhaust and cooling system have cooled sufficiently.
1. Drain engine coolant from radiator. Refer to CO-8, "
Draining".
CAUTION:
 Perform this step when the engine is cold.
 Never spill engine coolant on drive belt.
2. Remove reservoir tank. Refer to CO-13, "
Exploded View".
3. Remove drive belt. Refer to EM-20, "
Removal and Installation".
4. Remove power steering oil pump. Refer to ST-48, "
Exploded View".
5. Remove radiator. Refer to CO-13, "
Exploded View".
6. Remove front under cover. Refer to EXT-25, "
Exploded View".
7. Remove front wheels and tires. Refer to WT-64, "
Exploded View".
8. Remove A/C compressor. Refer to HA-30, "
Exploded View".
9. Remove alternator and alternator bracket. Refer to CHG-25, "
Exploded View".
10. Remove exhaust front tube (bank 1 and bank 2). Refer to EX-5, "
Exploded View".
1. Air fuel ratio sensor 1 (bank 2) 2. Exhaust manifold cover (bank 2) 3. Exhaust manifold and three way cat-
alyst (bank 2)
4. Gasket 5. Exhaust manifold and three way cat-
alyst (bank 1)6. Exhaust manifold cover (bank 1)
7. Air fuel ratio sensor 1 (bank 1)
Refer to GI-4, "
Components" for symbols in the figure.
JSBIA0389GB
Revision: 2010 May2011 QX56

ENGINE ASSEMBLYEM-99
< UNIT REMOVAL AND INSTALLATION >
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4WD models
Removal and InstallationINFOID:0000000006289577
WARNING:
 Situate the vehicle on a flat and solid surface.
 Place chocks at the front
and back of rear wheels.
 For engines not equipped with engi ne slingers, attach proper slingers and bolts described in PARTS
CATALOG.
CAUTION:
 Always be careful to work safely, and avo id forceful or uninstructed operations.
 Never start working until exhaust system and engine coolant are cool enough.
 If items or work required are not covered by th e engine section, refer to the applicable sections.
 Always use the support poin t specified for lifting.
 Use either 2-pole lift type or separate type lift as much as possible. If board-on type is used for
unavoidable reasons, support at r ear axle jacking point with transmi ssion jack or similar tool before
starting work, in preparat ion for the backward shift of the center of gravity.
 For supporting points fo r lifting and jacking point at rear axle, refer to GI-32, "
Garage Jack and
Safety Stand".
NOTE:
When removing/installing only the engine mounting, the hold engine assembly as instructed bellow:
1. Remove hood assembly. Refer to DLK-215, "
Exploded View".
2. Remove the following components and related parts:  Battery. Refer to PG-164, "
Exploded View".
 Battery tray.
 Power steering reservoir tank bracket. Refer to ST-54, "
Exploded View".
 Air cleaner case assembly and air duct. Refer to EM-27, "
Exploded View".
JPBIA4256GB
1. Heat shield plate (RH) 2. Engine mounting insulator (RH) 3. Engine mounting bracket (RH)
4. Engine mounting bracket (LH) 5. Engine mounting insulator (LH) 6. Heat shield plate (LH)
7. Rear engine mounting cross member 8. Rear engine mounting insulator 9. Dynamic damper
Refer to GI-4, "
Components" for symbols in the figure.
Revision: 2010 May2011 QX56