2011 INFINITI QX56 air suspension

C1803 AIR SUSPENSION EXH SOLSCS-75
< DTC/CIRCUIT DIAGNOSIS > [AIR LEVELIZER CONTROL SYSTEM]
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3. Check continuity between air levelizer contro l module harness connector and air compressor harness
connector.
4. Check continuity between air levelizer control module harness connector and ground.
Are the inspection results normal?
YES >> GO TO 3.
NO >> Repair or replace damaged part.
3.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
Is the inspection result normal?
YES >> Replace the air levelizer control module. Refer to SCS-94, "Removal and Installation".
NO >> Repair or replace damaged parts.
4.CHECK AIR COMPRESSOR GROUND
1. Turn ignition switch OFF.
2. Check continuity between air compressor harness connector and ground.
Are the inspection results normal?
YES >> GO TO 5.
NO >> Repair or replace damaged part.
5.CHECK AIR COMPRESSOR (EXHAUST SOLENOID)
Check the air compressor (exhaust solenoid). Refer to SCS-75, "
Component Inspection".
Is the inspection result normal?
YES >> Check intermittent incident. Refer to GI-40, "Intermittent Incident".
NO >> Replace the air compressor. Refer to SCS-95, "
Removal and Installation".
Component InspectionINFOID:0000000006256069
CAUTION:
 Keep the inside of air compressor free of dust.
 Keep the resin stick and resin pipe free of scratches and burrs.
1.CHECK AIR COMPRESSOR (EXHAUST SOLENOID)
1. Remove the air compressor. Refer to SCS-95, "
Removal and Installation".
Air levelizer control module Air compressor
Continuity
Connector Terminal Connector Terminal
B84 11 C12 4 Existed
Air levelizer control module
—Continuity
Connector Terminal
B84 11 Ground Not existed
Air compressor —Continuity
Connector Terminal
C12 3 Ground Existed
Revision: 2010 May2011 QX56

SCS-76
< DTC/CIRCUIT DIAGNOSIS >[AIR LEVELIZER CONTROL SYSTEM]
C1803 AIR SUSPENSION EXH SOL
2. Insert resin stick (A) 4.7 mm (0
.185 in) in diameter into either
one of the air compressor air tube holes to prevent leakage of
air.
3. Insert resin pipe (B) 4.7 mm (0.185 in) in diameter into the other
air tube hole and install air gauge (C) on the tip of the pipe.
4. Apply 12 V between air compressor connector terminal 1 and 2
until the air gauge reading reaches approximately 500 mm Hg
(0.67 MPa).
CAUTION:
 Never make the terminals short.
 Connect the fuse between th e terminals when applying
the voltage.
5. Apply 12 V between air compressor connector te rminal 3 and 4 for approximately 2 seconds.
CAUTION:
 Never make the terminals short.
 Connect the fuse between the termina ls when applying the voltage.
*: It takes approximately 2 minutes for the air gauge needle to stop moving.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Replace the air compressor. Refer to SCS-95, "
Removal and Installation".
JSEIA0248ZZ
(+) (fuse) (−)
Condition Status
Air compressor
Te r m i n a l
12 Apply 12 V between air compressor connector terminal 1 and 2
until the air gauge reading reaches approximately 500 mm Hg
(0.67 MPa). Air gauge needle remains at
the pressurized position.
(+) (fuse) (
−)
Condition Status
Air compressor
Te r m i n a l
43 Apply 12 V between air compressor connector terminal 3 and 4
for approximately 2 seconds. Air gauge reading lowers and
the needle stops moving.
Revision: 2010 May2011 QX56

C1804 VHCL HEIGHT ADJ UPSCS-77
< DTC/CIRCUIT DIAGNOSIS > [AIR LEVELIZER CONTROL SYSTEM]
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C1804 VHCL HEIGHT ADJ UP
DTC LogicINFOID:0000000006256070
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. Set vehicle in the unloaded vehicle status.
2. Start the engine and wait 150 seconds or more.
3. Perform “Self Diagnostic Result” in “E-SUS”.
Is
“C1804” detected ?
YES >> Go to SCS-77, "DiagnosisProcedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006256071
1.CHECK APPEARANCE
Visually check for malfunction of suspension component s, damage of air chamber of rear shock absorber,
installation malfunction, or defo rmation of vehicle height sensor.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Repaire or replace damaged parts.
2.CHECK AIR LEAK
Apply soapy water to air tube, connecting portions between air tube and each component, and air chamber of
rear shock absorber. Check for air leakage.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repaire or replace damaged parts.
3.CHECK AIR COMPRESSOR RELAY POWER SUPPLY
1. Turn ignition switch OFF.
2. Check 30A fuse (#I).
3. Disconnect air compressor relay connector.
4. Check voltage between air compressor relay harness connector and ground.
DTC Display item Malfunction detected condition Possible cause
C1804 VHCL HEIGHT ADJ UP The vehicle height is 15 mm (0.59 in) or more lower
than the reference height despite the output of air
compressor ON signal continuously for 120 seconds
by the air levelizer control module.  Harness or connector
Air compressor
 Air compressor relay
 Air levelizer control module
 Rear shock absorber (air cham-
ber)
 Vehicle height sensor
 Air tube
 Rear suspension component parts
 Overloaded
Revision: 2010 May2011 QX56

SCS-80
< DTC/CIRCUIT DIAGNOSIS >[AIR LEVELIZER CONTROL SYSTEM]
C1805 VHCL HE
IGHT ADJ DOWN
C1805 VHCL HEIGHT ADJ DOWN
DTC LogicINFOID:0000000006256074
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. Start the engine and wait 150 seconds or more.
2. Perform “Self Diagnostic Result” in “E-SUS”.
Is
“C1805” detected ?
YES >> Go to SCS-80, "DiagnosisProcedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006256075
1.CHECK APPEARANCE
Visually check for malfunction of suspension components, crush of air tube, installation malfunction, or defor-
mation of vehicle height sensor.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Repaire or replace damaged parts.
2.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
Is the inspection result normal?
YES >> Perform “STANDARD VEHICLE HEIGHT SETTING”. Refer to SCS-67, "Work Procedure".
NO >> Repair or replace damaged part.
DTC Display item Malfunction detected condition Possible cause
C1805 VHCL HEIGHT ADJ DOWN The vehicle height is 15 mm (0.59 in) or more raise than
the reference height despite the output of exhaust sole-
noid ON signal continuously for 120 seconds by the air
levelizer control module.  Harness or connector
 Vehicle height sensor
Air compressor
(exhaust sole-
noid)
Air tube
 Rear suspension component
parts
Revision: 2010 May2011 QX56

SCS-84
< DTC/CIRCUIT DIAGNOSIS >[AIR LEVELIZER CONTROL SYSTEM]
C1808 AIR SUS COMPRS FNCTN
C1808 AIR SUS COMPRS FNCTN
DTC LogicINFOID:0000000006256080
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. Set vehicle in the unloaded vehicle status.
2. Start the engine and wait 5 minutes or more.
3. Perform “Self Diagnostic Result” in “E-SUS”.
Is
“C1808” detected ?
YES >> Go to SCS-84, "DiagnosisProcedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006256081
1.CHECK APPEARANCE
Visually check for malfunction of suspension component s, damage of air chamber of rear shock absorber,
installation malfunction, or deformation of vehicle height sensor.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Repaire or replace damaged parts.
2.CHECK AIR LEAK
Apply soapy water to air tube, connecting portions between air tube and each component, and air chamber of
rear shock absorber. Check for air leakage.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repaire or replace damaged parts.
3.CHECK AIR COMPRESSOR RELAY POWER SUPPLY
1. Turn ignition switch OFF.
2. Check 30A fuse (#I).
3. Disconnect air compressor relay connector.
4. Check voltage between air compressor relay harness connector and ground.
DTC Display item Malfunction detected condition Possible cause
C1808 AIR SUS COMPRS FNCTN The cumulative operating time of the air compressor
reaches 180 seconds or more.
NOTE:
Cumulative time is cleared under the following condi-
tions:
 Ignition switch: OFF
 Exhaust conditions: satisfied [Vehicle height re-
mains 15 mm (0.59 in) or more higher than the ref-
erence height for 30 seconds.]  Harness or connector
 Vehicle height sensor
 Air compressor (exhaust sole-
noid)
 Air compressor relay
 Overloaded
 Rear shock absorber (air cham- ber)
 Rear suspension component parts
 Air tube
Revision: 2010 May2011 QX56

VEHICLE HEIGHT CANNOT BE RAISEDSCS-91
< SYMPTOM DIAGNOSIS > [AIR LEVELIZER CONTROL SYSTEM]
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SYMPTOM DIAGNOSIS
VEHICLE HEIGHT CANNOT BE RAISED
DescriptionINFOID:0000000006256092
Vehicle height remains in low status.
Diagnosis ProcedureINFOID:0000000006256093
1.CHECK APPEARANCE
Visually check for fuse, malfunction of suspension components, installation malfunction, or deformation of
vehicle height sensor.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Repaire or replace damaged parts.
2.PERFORM SELF-DIAGNOSIS
1. Turn ignition switch ON.
2. Select “Self Diagnostic Result” in “E-SUS”.
Are any DTC detected?
YES >> Refer to SCS-59, "DTC Index".
NO >> GO TO 3.
3.PERFORM STANDARD VEHICLE HEIGHT SETTING
Refer to SCS-67, "
Work Procedure".
Is the symptom improved?
YES >> INSPECTION END
NO >> Replace the air levelizer control module. Refer to SCS-94, "
Removal and Installation".
Revision: 2010 May2011 QX56

SCS-92
< SYMPTOM DIAGNOSIS >[AIR LEVELIZER CONTROL SYSTEM]
VEHICLE HEIGHT CANNOT BE LOWERED
VEHICLE HEIGHT CANNOT BE LOWERED
DescriptionINFOID:0000000006256094
Vehicle height remains in high status.
Diagnosis ProcedureINFOID:0000000006256095
1.CHECK APPEARANCE
Visually check for fuse, malfunction of suspension components, installation malfunction, or deformation of
vehicle height sensor.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Repaire or replace damaged parts.
2.PERFORM SELF-DIAGNOSIS
1. Turn ignition switch ON.
2. Select “Self Diagnostic Result” in “E-SUS”.
Are any DTC detected?
YES >> Refer to SCS-59, "DTC Index".
NO >> GO TO 3.
3.PERFORM STANDARD VEHICLE HEIGHT SETTING
Refer to SCS-67, "
Work Procedure".
Is the symptom improved?
YES >> INSPECTION END
NO >> Replace the air levelizer control module. Refer to SCS-94, "
Removal and Installation".
Revision: 2010 May2011 QX56

NOISE, VIBRATION AND HARSHNESS (NVH) TROUBLESHOOTINGST-29
< SYMPTOM DIAGNOSIS >
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NOISE, VIBRATION AND HARSHN ESS (NVH) TROUBLESHOOTING
NVH Troubleshooting ChartINFOID:0000000006225596
Use the chart below to find the cause of the symp tom. If necessary, repair or replace these parts.
×: ApplicableReference
ST-30, "
Inspection
"
ST-30, "
Inspection
"
ST-46, "
Inspection
"
ST-46, "
Inspection
"
ST-46, "
Inspection
"
ST-30, "
Inspection
"
ST-32, "
Inspection
"
ST-32, "
Inspection
"
EM-20, "
Checking
"
ST-32, "
Inspection
"—
ST-41, "
Exploded View
"
ST-35, "
Inspection
"
ST-34, "
Exploded View
"
ST-41, "
Exploded View
"
NVH in DLN section.
NVH in DLN section.
NVH in FAX, RAX, FSU, RSU section.
NVH in WT section.
NVH in WT section.
NVH in FAX, RAX section.
NVH in BR section.
Possible cause and SUSPECTED PARTS
Fluid level
Air in hydraulic system
Outer/inner socket ball joint swinging torque
Outer/inner socket ball joint rotating torque
Outer/inner socket ball joint end play
Steering fluid leakage
Steering wheel play
Steering gear rack sliding force
Drive belt looseness
Improper steering wheel
Improper installation or looseness of tilt lock lever
Mounting looseness
Steering column deformation or damage
Improper installation or looseness of steering column
Steering linkage looseness
PROPELLER SHAFT
DIFFERENTIAL
AXLE and SUSPENSION
TIRE
ROAD WHEEL
DRIVE SHAFT
BRAKE
Symptom Steering Noise
××××××××× ×× ×××××××
Shake × × × ×××××
Vibration ××××××××
Shimmy ×× × ××××
Judder ××××××
Revision: 2010 May2011 QX56