2011 INFINITI QX56 air suspension

RSU-14
< REMOVAL AND INSTALLATION >
SUSPENSION ARM
1. Move the ball joint at least ten times by hand to check for smooth movement.
2. Hook spring balance (A) at groove. Confirm spring balancemeasurement value is within specifications when ball stud
begins moving.
 If swing torque exceeds the standard range, replace suspension arm assembly.
Rotating Torque Inspection
1. Move the ball joint at least ten times by hand to check for smooth movement.
2. Check that rotating torque is within the specifications.
 If rotating torque exceeds the standard range, replace suspension arm assembly.
Axial End Play Inspection
1. Move the ball joint at least ten times by hand to check for smooth movement.
2. Move tip of ball stud in axial direction to check for looseness.
 If axial end play exceeds the standard r ange, replace suspension arm assembly.
INSPECTION AFTER INSTALLATION
1. Check wheel alignment. Refer to RSU-6, "Inspection".
2. Adjust neutral position of steering angle sensor. Refer to BRC-64, "
Work Procedure".
3. Adjust levelizer adjustment of height sensor. Refer to EXL-61, "
LEVELIZER ADJUSTMENT : Special
Repair Requirement".
4. Check standard vehicle height setting of vehicle height sensor. Refer to SCS-67, "
Work Procedure".
ADJUSTMENT AFTER INSTALLATION (WITH HBMC)
Bleed air from the HBMC. Refer to SCS-18, "Work Procedure".
Swing torque : Refer to
RSU-20, "
Ball Joint".
JPEIA0005ZZ
Rotating torque : Refer to RSU-20, "Ball Joint".
Axial end play : Refer to RSU-20, "
Ball Joint".
Revision: 2010 May2011 QX56

REAR SUSPENSION MEMBERRSU-19
< UNIT REMOVAL AND INSTALLATION >
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16. Remove final drive. Refer to DLN-201, "Removal and Installation".
17. Remove rear tube assembly A and rear tube assembly B. (With HBMC) Refer to SCS-44, "
REAR TUBE
ASSEMBLY : Removal and Installation".
18. Set suitable jack under rear suspension member.
19. Slowly lower jack, then remove rear suspension member, suspension arm, front lower link, wheel hub and housing from vehicle as a unit.
20. Remove mounting bolts and nuts, then remove suspension arm, front lower link, wheel hub and housing from rear suspension member.
21. Perform inspection after removal. Refer to RSU-19, "
Inspection and Adjustment".
INSTALLATION
Note the following, and install in the reverse order of the removal.
 Perform the final tightening of each of parts under unladen conditions, which were removed when removing
rear suspension assembly.
 Perform inspection after installation. Refer to RSU-19, "
Inspection and Adjustment".
 Perform adjustment after installation. (With HBMC) Refer to RSU-19, "
Inspection and Adjustment".
Inspection and AdjustmentINFOID:0000000006225678
INSPECTION AFTER REMOVAL
Check rear suspension member for deformation, cracks, or any other damage. Replace if necessary.
INSPECTION AFTER INSTALLATION
1. Adjust parking brake operation (stroke). Refer to PB-3, "Inspection and Adjustment".
2. Check wheel alignment. Refer to RSU-6, "
Inspection".
3. Adjust neutral position of steering angle sensor. Refer to BRC-64, "
Work Procedure".
4. Adjust levelizer adjustment of height sensor. Refer to EXL-61, "
LEVELIZER ADJUSTMENT : Special
Repair Requirement".
5. Check standard vehicle height setting of vehicle height sensor. Refer to SCS-67, "
Work Procedure".
6. Check wheel sensor harness for proper connection. Refer to BRC-135, "
REAR WHEEL SENSOR :
Exploded View"
ADJUSTMENT AFTER INSTALLATION (WITH HBMC)
Bleed air from the HBMC. Refer to SCS-18, "Work Procedure".
Revision: 2010 May2011 QX56

SCS-1
SUSPENSION
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SECTION SCS
A
B
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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

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

SCS-6
< PREPARATION >[HBMC]
PREPARATION
PREPARATION
PREPARATION
Special Service ToolsINFOID:0000000006255997
The actual shapes of Kent-Moore tool
s may differ from those of special service tools illustrated here.
Commercial Service ToolsINFOID:0000000006414888
Tool number
(Kent-Moore No.)
Tool name Description
KV40107700
(—)
Suspension oil pump  Air bleeding
 System diagnosis
KV40108000
(—)
Oil pressure gauge System pressure check
KV40108400
(—)
Leak check plug Shock absorber leakage check
JSEIA0183ZZ
JSEIA0184ZZ
JSEIA0185ZZ
Tool name
Description
Power tool Loosening bolts and nuts
PBIC0190E
Revision: 2010 May2011 QX56

SCS-18
< BASIC INSPECTION >[HBMC]
AIR BLEEDING METHOD
AIR BLEEDING METHOD
Work ProcedureINFOID:0000000006256011
WARNING:
 Always check the piping for loose co
nnections, damage, or twists before starting operation, since
pressure in hydraulic circuit b ecomes high during 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.
CAUTION:
 Clean surrounding areas of oil injection jack and air bleeder using steam before starting operation,
since there may be mud on it.
 Clean suspension oil pump (special servi ce tool: KV40107700) jack with steam before use.
 Check system pressure again 1 day or more after bleeding operation is complete, since system pres-
sure may decrease when air bleeding is insufficient.
1. Lift up the vehicle.
2. Remove protector of PPMU.
3. Remove cap of oil injection jack.
4. Install hose (A) of a suspension oil pump (SST: KV40107700) to oil injection jack.
CAUTION:
Jack must be securely inserted until a click sound can be
heard.
5. Loosen pressure reducing valve (A) of hose portion of suspen- sion oil pump.
6. Set knob (A) of suspension oil pump to the direction as shown in the figure.
7. Close pressure reducing valve of hose portion of suspension oil pump while sending oil by applying pressure using suspension
oil pump. (Air bleeding in hose is complete.)
JSEIA0189ZZ
JSEIA0190ZZ
JSEIA0191ZZ
Revision: 2010 May2011 QX56

AIR BLEEDING METHODSCS-19
< BASIC INSPECTION > [HBMC]
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8. Loosen needle valves A, C, and E of PPMU by approximately 2 rotations.
CAUTION:
Never loosen the needle valve more than required.
9. Install bleeder tube and drain tank to bleeder valve in upper side of rear shock absorber RH.
10. Loosen bleeder valve and bleed air while sending oil by applying pressure using suspension oil pump, and then quickly tighten air
bleeder.
CAUTION:
Be careful that oil in suspensi on oil pump is not at half or
less.
11. Repeat step 10 until no air appears in bleeder tube.
12. Tighten bleeder valve to the specified torque. Refer to SCS-32, "
FRONT TUBE ASSEMBLY : Exploded
View" (front shock absorber), SCS-39, "PPMU, MIDDLE TUBE ASSEMB LY, PPMU PIPE : Exploded
View" (upper side of rear shock absorber).
13. Perform operation according to steps 9 to 12 in the order of rear shock absorber RH (lower side) → front
shock absorber RH (upper side and lower side) → rear shock absorber LH (upper side and lower side) →
front shock absorber LH (upper side and lower side).
14. Repeat steps 9 to 13 (2nd turn).
15. Refer to the figure and send oil by applying pressure.
16. Tighten needle valves A, C, and E of PPMU to the specified torque.
17. Set knob (A) of suspension oil pump to the direction as shown in the figure and check that reading of pressure gauge is 0 MPa.
18. Remove hose of suspension oil pump.
19. Install cap of oil injection jack.
20. Install protector of PPMU. Refer to SCS-39, "
PPMU, MIDDLE
TUBE ASSEMBLY, PPMU PIPE : Exploded View".
Lower side of rear shock absorber
Tightening torque : 8.3 N·m (0.85 kg-m, 73 in-lb)
JSEIA0187ZZ
JSEIA0236GB
Tightening torque : 8.3 N·m (0.85 kg-m, 73 in-lb)
JSEIA0193ZZ
Revision: 2010 May2011 QX56