2011 INFINITI QX56 air suspension

DIFFERENCE IN APPEARANCESCS-29
< SYMPTOM DIAGNOSIS > [HBMC]
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SYMPTOM DIAGNOSIS
DIFFERENCE IN APPEARANCE
DescriptionINFOID:0000000006256016
While the vehicle is stopped, the difference of vehicle height of right side and left side (between wheel center
and wheel arch) is 25 mm (0.98 in) or more.
Inspection ProcedureINFOID:0000000006256017
1.CHECK APPEARANCE
1. Visually check that the exterior parts (e.g. suspension spring) have no malfunctions.
2. Visually check tube and pipe for crush or oil leakage.
Is the check result normal?
YES >> GO TO 2.
NO >> Repair or replace damaged parts.
2.CHECK CLOGGING OF ORIFICE IN PPMU
1. Install an oil pressure gauge (SST: KV40108000) (A) to oil injec- tion jack.
CAUTION:
 Clean surrounding areas of oi l injection jack using steam
before starting oper ation, since there may be mud on it.
 Clean oil pressure gauge (special service tool:
KV40108000) jack with steam before use.
 Jack must be securely inserted until a click sound can be heard.
 Pressure reducing valve (B) of the oil pressure gauge
must be closed.
2. Loosen needle valves A and C of PPMU by approximately 2 rotations for check changes in vehicle height.
CAUTION:
Never loosen the needle valve more than required.
3. Tighten needle valve A and C of PPMU to the specified torque after the inspection.
Does the vehicle height change 10 mm (0.39 in) or more?
YES >> For detailed inspection of clogging of orifice in PPMU, refer to SCS-27, "
Work Procedure".
NO >> INSPECTION END
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Tightening torque : 8.3 N· m (0.85 kg-m, 73 in-lb)
JSEIA0187ZZ
Revision: 2010 May2011 QX56

SCS-30
< SYMPTOM DIAGNOSIS >[HBMC]
LARGE ROLL ANGLE
LARGE ROLL ANGLE
DescriptionINFOID:0000000006256018
During cornering, inclination of the vehi
cle to outer side of corner is large.
Inspection ProcedureINFOID:0000000006256019
1.CHECK APPEARANCE
1. Visually check that the exterior parts (e.g. suspension spring) have no malfunctions.
2. Visually check tube and pipe for crush or oil leakage.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Repair or replace damaged parts.
2.CHECK NEEDLE VALVE OF PPMU
Check that needle valves A and C are tightened to the specified
torque.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Tighten to the specified torque.
3.SYSTEM PRESSURE CHECK
Check system pressure. Refer to SCS-15, "
Work Procedure".
Is the inspection result normal?
YES >> GO TO 4.
NO >> Perform adjustment of system pressure. Refer to SCS-18, "
Work Procedure".
4.CHECK INTERNAL LEAKAGE
Check internal leakage. Refer to SCS-20, "
Work Procedure".
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 5.
5.CHECK MALFUNCTIONING PART
Identify malfunctioning part. Refer to SCS-22, "
Work Procedure".
Does the pressure increase?
YES >> Replace the PPMU. Refer to SCS-39, "PPMU, MIDDLE TUBE ASSEMBLY, PPMU PIPE :
Removal and Installation".
NO >> GO TO 6.
6.CHECK SHOCK ABSORBER
Identify malfunctioning shock absorber. Refer to SCS-24, "
Work Procedure".
>> Replace identified shock absorber. Refer to FSU-10, "
Removal and Installation" (front), RSU-8,
"Removal and Installation" (rear).
Tightening torque : 8.3 N·
m (0.85 kg-m, 73 in-lb)
JSEIA0187ZZ
Revision: 2010 May2011 QX56

SCS-34
< REMOVAL AND INSTALLATION >[HBMC]
HYDRAULIC BODY-MOTION CONTROL SYSTEM
3. Disconnect pipe (A) of accumulator assembly RH from right side
3-way (B).
4. Disconnect lower side pipe (B) of front shock absorber RH.
5. Remove protector A with power tool.
6. Remove mounting bolts of right side 3-way.
7. Remove protector B with power tool.
8. Remove mounting bolts of each bracket.
9. Remove front tube assembly B from the vehicle.
10. Perform inspection after removal. Refer to SCS-34, "
FRONT
TUBE ASSEMBLY : Inspection".
INSTALLATION
Note the following, and install in the reverse order of removal.
 Apply genuine NISSAN hydraulic suspension fluid to O-ring.
 Check connection portion of each piping for dirt or dust.
 Completely insert guide (A) to guide hole on frame when installing
left side 3-way.
 For tightening torque for pipe of accumulator assembly LH, refer to SCS-35, "
ACCUMULATOR : Exploded View".
 For tightening torque for pipe of accumulator assembly RH, refer to
SCS-35, "
ACCUMULATOR : Exploded View".
FRONT TUBE ASSEMBLY : InspectionINFOID:0000000006256023
INSPECTION AFTER REMOVAL
 O-ring must be free of scratches and damage.
 Pipe and tube must be free of scratches and damage.
INSPECTION AFTER INSTALLATION
Check oil leakage, twists, deformation, cont act with other parts, and loose connections.
ADJUSTMENT AFTER INSTALLATION
Perform air bleeding. Refer to SCS-18, "Work Procedure".
ACCUMULATOR
JSEIA0197ZZ
A : Upper side pipe
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Revision: 2010 May2011 QX56

SCS-46
< REMOVAL AND INSTALLATION >[HBMC]
HYDRAULIC BODY-MOTION CONTROL SYSTEM
3. Remove lower side pipe (A) of rear shock absorber RH.
4. Remove pipe (A) from left side rear joint (B).
5. Remove mounting bolts of bracket of rear tube assembly B.
6. Remove mounting bolts of bracket of rear left brake hose, and
then free hose.
7. Remove rear tube assembly B from the vehicle.
8. Perform inspection after removal. Refer to SCS-46, "
REAR
TUBE ASSEMBLY : Inspection".
INSTALLATION
Note the following, and install in the reverse order of removal.
 Apply genuine NISSAN hydraulic suspension fluid to O-ring.
 Check connection portion of each piping for dirt or dust.
REAR TUBE ASSEMBLY : InspectionINFOID:0000000006256034
INSPECTION AFTER REMOVAL
 O-ring must be free of scratches and damage.
 Pipe and tube must be free of scratches and damage.
INSPECTION AFTER INSTALLATION
Check oil leakage, twists, deformation, contact with other parts, and loose connections.
ADJUSTMENT AFTER INSTALLATION
Perform air bleeding. Refer to SCS-18, "Work Procedure".
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Revision: 2010 May2011 QX56

DESCRIPTIONSCS-49
< SYSTEM DESCRIPTION > [AIR LEVELIZER CONTROL SYSTEM]
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SYSTEM DESCRIPTION
DESCRIPTION
DescriptionINFOID:0000000006256039
 Corrects sinkage of vehicle rear that occurs in laden or towing conditions.
 Maintains vehicle height at a constant level and improv es riding comfort by charging or discharging air in air
chamber of rear shock absorber, according to signal from vehicle height sensor installed to rear suspension.
Revision: 2010 May2011 QX56

STRUCTURE AND OPERATIONSCS-53
< SYSTEM DESCRIPTION > [AIR LEVELIZER CONTROL SYSTEM]
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Vehicle Height SensorINFOID:0000000006256048
Vehicle height sensor is installed between rear suspension member
(1) and rear lower link (2).
Since arm (A) portion and rod (B) portion are ball joint type, distance
between rear suspension member and rear lower link shortens when
vehicle height of vehicle rear lowers because of laden or towing con-
ditions, and arm portion changes to the status that is higher in its left
side as shown in the figure.
This angle change in arm portion is transmitted to the air levelizer
control module according to electric signal.
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Revision: 2010 May2011 QX56

C1801 VHCL HEIGHT SENSORSCS-69
< DTC/CIRCUIT DIAGNOSIS > [AIR LEVELIZER CONTROL SYSTEM]
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DTC/CIRCUIT DIAGNOSIS
C1801 VHCL HEIGHT SENSOR
DTC LogicINFOID:0000000006256062
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
If “DTC CONFIRMATION PROCEDURE” has been previous ly conducted, always turn ignition switch OFF
andwait at least 10 seconds before conducting the next test.
>> GO TO 2.
2.CHECK DTC DETECTION
With CONSULT-III
1. Turn ignition switch ON and wait 60 seconds or more.
2. Perform “Self Diagnostic Results” in “E-SUS”.
Is
“C1801” detected ?
YES >> Go to SCS-69, "DiagnosisProcedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006256063
1.CHECK APPEARANCE
Visually check for malfunction of suspension components, installing malfunction, or deformation of vehicle
height sensor.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Repaire or replace damaged parts.
2.CHECK POWER SUPPLY CIRCUIT (PART 1)
1. Disconnect vehicle height sensor connector.
2. Turn ignition switch ON. CAUTION:
Never start the engine.
3. Check voltage between vehicle height sensor harness connector and ground.
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 3.
3.CHECK POWER SUPPLY CIRCUIT (PART 2)
1. Turn ignition switch OFF.
2. Disconnect air levelizer control module connector.
DTC Display itemI Malfunction detected condition Possible cause
C1801 VHCL HEIGHT SENSOR Signal voltage of the vehicle height sensor remains 0.2
V or less or 4.6 V or more continuously for 60 seconds
during sensor voltage (4.5 – 5.5 V) output by the air lev-
elizer control module.  Harness or connectors
(Sensor circuit is open.)
 Vehicle height sensor
 Air levelizer control module
 Rear suspension component parts
Vehicle height sensor —Voltage
Connector Terminal
C13 1 Ground 4.5 – 5.5 V
Revision: 2010 May2011 QX56

SCS-74
< DTC/CIRCUIT DIAGNOSIS >[AIR LEVELIZER CONTROL SYSTEM]
C1803 AIR SUSPENSION EXH SOL
C1803 AIR SUSPENSION EXH SOL
DTC LogicINFOID:0000000006256067
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
If “DTC CONFIRMATION PROCEDURE” has been previous ly conducted, always turn ignition switch OFF
andwait at least 10 seconds before conducting the next test.
>> GO TO 2.
2.CHECK DTC DETECTION
With CONSULT-III
1. Turn ignition switch ON and wait 10 seconds or more.
2. Select “EXHAUST SOLENOID” in “Active Test” in “E-SUS”.
3. Touch “ON” and wait 5 seconds or more.
4. Select “Self Diagnostic Result” in “E-SUS”.
Is
“C1803” detected ?
YES >> Go to SCS-74, "DiagnosisProcedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006256068
1.CHECK EXHAUST SOLENOID ON SIGNAL FROM AIR LEVELIZER CONTROL MODULE
CONSULT-III
1. Disconnect air compressor harness connector.
2. Turn ignition switch ON. CAUTION:
Never start the engine.
3. Select “EXHAUST SOLENOID” in “Active Test” in “E-SUS”.
4. Touch “ON”.
5. While operating test item, check voltage bet ween air compressor harness connector and ground.
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN AIR LEVELIZE R CONTROL MODULE AND AIR COMPRESSOR
1. Turn ignition switch OFF.
2. Disconnect air levelizer control module harness connector.
DTC Display item Malfunction detected condition Possible cause
C1803 AIR SUS EXH SOL  Output voltage of the exhaust solenoid remains 9 V
or less continuously for 5 seconds during exhaust
solenoid ON signal output by the air levelizer con-
trol module.
 Output voltage of the exhaust solenoid remains 2 V
or more continuously for 10 seconds during ex-
haust solenoid ON signal output by the air levelizer
control module.  Harness or connector
 Exhaust solenoid
 Air levelizer control module
Air compressor
—Voltage
Connector Terminal
C12 4 Ground 9 – 16 V
Revision: 2010 May2011 QX56