2011 INFINITI QX56 steering

SCS-1
SUSPENSION
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SECTION SCS
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O PCONTENTS
SUSPENSION CONTROL SYSTEM
HBMC
PRECAUTION ................ ...............................
4
PRECAUTIONS .............................................. .....4
Precaution for Supplemental Restraint System
(SRS) "AIR BAG" and "SEAT BELT PRE-TEN-
SIONER" ............................................................. ......
4
Precaution Necessary for Steering Wheel Rota-
tion after Battery Disconnect .....................................
4
Precaution for Procedure without Cowl Top Cover ......5
Precaution for Hydraulic Body-Motion Control
System ......................................................................
5
PREPARATION ............................................6
PREPARATION .............................................. .....6
Special Service Tools .......................................... ......6
Commercial Service Tools ........................................6
SYSTEM DESCRIPTION ..............................7
DESCRIPTION ............................................... .....7
Description .......................................................... ......7
COMPONENT PARTS ........................................8
Component Parts Location .................................. ......8
Component Description .............................................8
STRUCTURE AND OPERATION ........................9
Hydraulic Body-Motion Control System .............. ......9
Shock Absorber .........................................................9
PPMU ......................................................................10
Accumulator ............................................................11
PPMU Pipe ..............................................................11
SYSTEM .............................................................12
System Diagram .................................................. ....12
System Description .................................................12
Component Description ...........................................14
BASIC INSPECTION ...................................15
CHECK SYSTEM PRESSURE .........................15
Work Procedure ................................................... ....15
PRESSURE REDUCING METHOD ..................17
Work Procedure .......................................................17
AIR BLEEDING METHOD ................................18
Work Procedure .......................................................18
CHECK INTERNAL LEAKAGE ........................20
Work Procedure .......................................................20
CHECK FOR MALFUNCTION ..........................22
Work Procedure .......................................................22
CHECK SHOCK ABSORBER FOR MAL-
FUNCTION ....................................... .................
24
Work Procedure ................................................... ....24
CHECK ORIFICE FOR CLOGGING .................27
Work Procedure .......................................................27
SYMPTOM DIAGNOSIS ..............................29
DIFFERENCE IN APPEARANCE .....................29
Description ........................................................... ....29
Inspection Procedure ...............................................29
LARGE ROLL ANGLE ......................................30
Description ...............................................................30
Inspection Procedure ...............................................30
REMOVAL AND INSTALLATION ...............31
HYDRAULIC BODY-MOTION CONTROL
SYSTEM ............................................................
31
Hydraulic Piping ................................................... ....31
FRONT TUBE ASSEMBLY .......................................31
FRONT TUBE ASSEMBLY : Exploded View ...... ....32
FRONT TUBE ASSEMBLY : Removal and Instal-
lation ........................................................................
32
FRONT TUBE ASSEMBLY : Inspection ..................34
Revision: 2010 May2011 QX56

SCS-2
ACCUMULATOR ......................................................34
ACCUMULATOR : Exploded View .........................35
ACCUMULATOR : Removal and Installation ..........35
ACCUMULATOR : Inspection ................................38
ACCUMULATOR : Disposal ...................................38
PPMU, MIDDLE TUBE ASSEMBLY, PPMU PIPE ...38
PPMU, MIDDLE TUBE ASSEMBLY, PPMU PIPE
: Exploded View ......................................................
39
PPMU, MIDDLE TUBE ASSEMBLY, PPMU PIPE
: Removal and Installation ......................................
39
PPMU, MIDDLE TUBE ASSEMBLY, PPMU PIPE
: Inspection .............................................................
43
PPMU, MIDDLE TUBE ASSEMBLY, PPMU PIPE
: Disposal ................................................................
43
REAR TUBE ASSEMBLY ...................................... ...43
REAR TUBE ASSEMBLY : Exploded View ............44
REAR TUBE ASSEMBLY : Removal and Installa-
tion ....................................................................... ...
44
REAR TUBE ASSEMBLY : Inspection ...................46
AIR LEVELIZER CONTROL SYSTEM
PRECAUTION ....... ....................... ...............
47
PRECAUTIONS .............................................. ...47
Precaution for Supplemental Restraint System
(SRS) "AIR BAG" and "SEAT BELT PRE-TEN-
SIONER" .............................................................. ...
47
Precaution Necessary for Steering Wheel Rota-
tion after Battery Disconnect ..................................
47
Precaution for Procedure without Cowl Top Cover ...48
Precaution for Air Levelizer Control System ...........48
SYSTEM DESCRIPTION ............................49
DESCRIPTION ................................................ ...49
Description ........................................................... ...49
COMPONENT PARTS .......................................50
Component Parts Location .................................. ...50
Component Description ..........................................50
Air Levelizer Control Module ..................................51
Vehicle Height Sensor ............................................51
Air Compressor .......................................................51
Air Compressor Relay ............................................51
CK SUSP Indicator Lamp .......................................51
STRUCTURE AND OPERATION ......................52
Rear Shock Absorber .......................................... ...52
Vehicle Height Sensor ............................................53
SYSTEM .......................................................... ...54
System Diagram .................................................. ...54
System Description .................................................54
Fail-safe ..................................................................55
DIAGNOSIS SYSTEM (AIR LEVELIZER
CONTROL MODULE) ........................................
56
CONSULT-III Function ........................................ ...56
ECU DIAGNOSIS INFORMATION .............58
AIR LEVELIZER CONTROL MODULE .......... ...58
Reference Value .................................................. ...58
Fail-safe ..................................................................59
DTC Inspection Priority Chart .................................59
DTC Index ...............................................................59
WIRING DIAGRAM ....................................61
AIR LEVELIZER CONTROL SYSTEM ........... ...61
Wiring Diagram .................................................... ...61
BASIC INSPECTION ..................................65
DIAGNOSIS AND REPAIR WORKFLOW ...... ...65
Work Flow ............................................................ ...65
Diagnostic Work Sheet ...........................................66
STANDARD VEHICLE HEIGHT SETTING .......67
Description ........................................................... ...67
Work Procedure ......................................................67
DTC/CIRCUIT DIAGNOSIS ........................69
C1801 VHCL HEIGHT SENSOR .................... ...69
DTC Logic ............................................................ ...69
Diagnosis Procedure ..............................................69
Component Inspection ............................................70
C1802 AIR SUS COMPRS RELAY ...................72
DTC Logic ............................................................ ...72
Diagnosis Procedure ..............................................72
C1803 AIR SUSPENSION EXH SOL ................74
DTC Logic ............................................................ ...74
Diagnosis Procedure ..............................................74
Component Inspection ............................................75
C1804 VHCL HEIGHT ADJ UP .........................77
DTC Logic ............................................................ ...77
Diagnosis Procedure ..............................................77
Component Inspection (Air Compressor Relay) .....79
Component Inspection (Air Compressor) ............. ...79
C1805 VHCL HEIGHT ADJ DOWN ...................80
DTC Logic ............................................................ ...80
Diagnosis Procedure ..............................................80
C1806 VHCL HEIGHT SEN FIX ........................81
DTC Logic ............................................................ ...81
Diagnosis Procedure ...............................................81
C1807 VHCL HEIGHT SEN VOLT ....................82
DTC Logic ............................................................ ...82
Diagnosis Procedure ..............................................82
C1808 AIR SUS COMPRS FNCTN ...................84
DTC Logic ............................................................ ...84
Diagnosis Procedure ..............................................84
U1000 CAN COMM CIRCUIT ............................87
Revision: 2010 May2011 QX56

SCS-4
< PRECAUTION >[HBMC]
PRECAUTIONS
PRECAUTION
PRECAUTIONS
Precaution for Supplemental Restraint S
ystem (SRS) "AIR BAG" and "SEAT BELT
PRE-TENSIONER"
INFOID:0000000006256134
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 w hether 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 inopera tive, which could increase the risk of personal injury or death in
the event of a collision that would result in air bag inflation, all maintenance must be performed by
an authorized NISS AN/INFINITI dealer.
 Improper maintenance, including in correct removal and installation of the SRS, can lead to personal
injury caused by unintent ional activation of the system. For re moval of Spiral Cable and Air Bag
Module, see the “SRS AIR BAG”.
 Do not use electrical test equipmen t 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 minu tes before performing any service.
Precaution Necessary for Steering W heel Rotation after Battery Disconnect
INFOID:0000000006256136
NOTE:
 Before removing and installing any control units, first tu rn the push-button ignition switch to the LOCK posi-
tion, then disconnect bot h 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.
If turning the steering wheel is required with the bat tery 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.
Revision: 2010 May2011 QX56

PRECAUTIONSSCS-5
< PRECAUTION > [HBMC]
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5. When the repair work is completed, re-connect both 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 ignition switch is turned to LOCK position.)
6. Perform self-diagnosis check of a ll control units using CONSULT-III.
Precaution for Procedure without Cowl Top CoverINFOID:0000000006256138
When performing the procedure after removing cowl top cover, cover
the lower end of windshield with urethane, etc.
Precaution for Hydraulic Body-Motion Control SystemINFOID:0000000006255996
WARNING:
 Always check the piping for loose co nnections, damage, or twists before starting operation, since
pressure in hydraulic circuit becom es high during air bleeding operation.
 When repairing or replacing a malfunctioning pa rt, always release pressure from hydraulic circuit,
since dangerous conditions may be created when oil leakage occurs during air bleeding operation.
 Clean surrounding areas of oil inlet and air bleeder usi ng steam before starting operation, since there may
be mud on it.
 Always decrease pressure when removing a system related part, since system pressure is high.
 Seal the removed part using vinyl tape for preventi ng dirt from getting on or entering the removed part.
 Check system pressure again 1 day or more after bleeding operation is complete, since system pressure may decrease when air bleeding is insufficient.
 Use Genuine NISSAN Hydraulic Suspension Fluid for suspension fluid.
 Never reuse drained suspension fluid.
 Check for suspension fluid leakage after removing a system-related part.
PIIB3706J
Revision: 2010 May2011 QX56

DESCRIPTIONSCS-7
< SYSTEM DESCRIPTION > [HBMC]
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SYSTEM DESCRIPTION
DESCRIPTION
DescriptionINFOID:0000000006255998
 Hydraulic body-motion control s ystem is adopted, which makes shock absorber stroke appropriately by
hydraulic pressure according to driving scenes.
 The adoption of this system allows the reduction in a ro ll angle (i.e. vehicle body tilt angle at cornering) to
improve steering stability and ride quality during travel on level roads. Furthermore, the use of this system
improves the running performance on rough roads by shock absorption and quality tire adhesion through
maximized stroke.
Revision: 2010 May2011 QX56

STRUCTURE AND OPERATIONSCS-9
< SYSTEM DESCRIPTION > [HBMC]
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STRUCTURE AND OPERATION
Hydraulic Body-Moti on Control SystemINFOID:0000000006256001
Shock AbsorberINFOID:0000000006256002
The use of accumulator-generated pressure responsive to driving conditions or pressure generated by oil flow
to the upper/lower chamber improves the steering stabili ty at curving, in addition to the running performance
and a ride quality during off-road travel.
FRONT SIDE
Oil enters from oil inlet outlet hole (A) and flows into lower chamber (3) via outside oil path of cylinder inside.
Oil enters from oil inlet outlet hole (B) and flows into upper chamber (1). With the pressure difference between
oil flowed into the upper chamber and lower chamber, the piston (2) moves up and down and conveys a force
generated through this motion to the tires.
1. Middle tube assembly RH 2. Accumulator assembly RH 3. Front tube assembly A
4. Front tube assembly B 5. Accumulator assembly LH 6. PPMU pipe A
7. PPMU assembly 8. Middle tube assembly LH 9. PPMU pipe B
10. Rear tube assembly A 11. Rear tube assembly B
:Vehicle front
JSEIA0228ZZ
Revision: 2010 May2011 QX56

PRECAUTIONSSCS-47
< PRECAUTION > [AIR LEVELIZER CONTROL SYSTEM]
C
D
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G H
I
J
K L
M A
B
SCS
N
O P
PRECAUTION
PRECAUTIONS
Precaution for Supplemental Restraint System (SRS) "AIR BAG" and "SEAT BELT
PRE-TENSIONER"
INFOID:0000000006256135
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:0000000006256137
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.
If turning the steering wheel is required with the batte ry 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 wil l remain released with both battery cables discon-
nected and the steering wheel can be turned.
4. Perform the necessary repair operation.
Revision: 2010 May2011 QX56

SCS-48
< PRECAUTION >[AIR LEVELIZER CONTROL SYSTEM]
PRECAUTIONS
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 Procedure without Cowl Top CoverINFOID:0000000006256139
When performing the procedure after removing cowl top cover, cover
the lower end of windshield with urethane, etc.
Precaution for Air Levelizer Control SystemINFOID:0000000006256038
 Never allow water and dust to enter the inside of air compressor.
 Never disassemble the vehicle height sensor.
PIIB3706J
Revision: 2010 May2011 QX56