INFINITI QX56 2011 Factory Service Manual

C1801 VHCL HEIGHT SENSORSCS-71
< DTC/CIRCUIT DIAGNOSIS > [AIR LEVELIZER CONTROL SYSTEM]
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1. Remove the vehicle height sensor. Refer to SCS-98, "Removal and Installation".
2. Check resistance between vehicle height sensor connector ter- minals.
Are the inspection results normal?
YES >> 1. Install the vehicle height sensor. Refer to SCS-94, "Removal and Installation".
2. Perform “STANDARD VEHICLE HEIGHT SETTING”. Refer to SCS-67, "
Work Procedure".
NO >> Replace the vehicle height sensor. Refer to SCS-98, "
Removal and Installation".
Vehicle height sensor
Condition Resistance (Approx.)
Te r m i n a l
12 A position 1.9 – 3.0 k
Ω
B position 320 – 680 Ω
1 3 Always 1.6 – 2.4 k Ω
23 A position 320 – 680
Ω
B position 1.9 – 3.0 k Ω
JSEIA0249ZZ
Revision: 2010 May2011 QX56

SCS-72
< DTC/CIRCUIT DIAGNOSIS >[AIR LEVELIZER CONTROL SYSTEM]
C1802 AIR SUS COMPRS RELAY
C1802 AIR SUS COMPRS RELAY
DTC LogicINFOID:0000000006256065
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 “COMPRESSOR” in “Active Test” in “E-SUS”.
3. Touch “ON” and wait 5 seconds or more.
4. Select “Self Diagnostic Result” in “E-SUS”.
Is
“C1802” detected ?
YES >> Go to SCS-72, "DiagnosisProcedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006256066
1.CHECK AIR COMPRESSOR ON SIGNAL FROM AIR LEVELIZER CONTROL MODULE
CONSULT-III
1. Disconnect air compressor relay connector.
2. Turn ignition switch ON. CAUTION:
Never start the engine.
3. Select “COMPRESSOR” in “Active Test” in “E-SUS”.
4. Touch “ON”.
5. While operating test item, check voltage betw een air compressor relay harness connector and ground.
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN AIR LEVELIZER CO NTROL MODULE AND AIR COMPRESSOR RELAY
1. Turn ignition switch OFF.
2. Disconnect air levelizer control module connector.
DTC Display item Malfunction detected condition Possible cause
C1802 AIR SUS COMPRS RELAY  Output voltage of the air compressor relay remains
9 V or less continuously for 5 seconds during air
compressor ON signal output by the air levelizer
control module.
 Output voltage of the air compressor relay remains
2 V or more continuously for 10 seconds during air
compressor OFF signal output by the air levelizer
control module.  Harness or connector
 Air compressor relay
 Air levelizer control module
Air compressor relay
—Voltage
Connector Terminal
E116 2 Ground 9 – 16 V
Revision: 2010 May2011 QX56

C1802 AIR SUS COMPRS RELAYSCS-73
< DTC/CIRCUIT DIAGNOSIS > [AIR LEVELIZER CONTROL SYSTEM]
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3. Check continuity between air levelizer control module harness connector and air compressor relay har-
ness connector.
4. Check continuity between air levelizer control module harness connector and ground.
5. Check voltage 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 RELAY GROUND
1. Turn ignition switch OFF.
2. Check continuity between air compressor relay harness connector and ground.
Is the inspection result normal?
YES >> GO TO 5.
NO >> Repair or replace damaged part.
5.CHECK AIR COMPRESSOR RELAY
1. Remove the air compressor relay. Refer to SCS-50, "
Component Parts Location".
2. Check continuity between air compressor relay harness connector terminals.
Is the inspection result normal?
YES >> Check intermittent incident. Refer to GI-40, "Intermittent Incident".
NO >> Replace the air compressor relay. Refer to SCS-50, "
Component Parts Location".
Air levelizer control module Air compressor relay
Continuity
Connector Terminal Connector Terminal
B84 3 E116 2 Existed
Air levelizer control module
—Continuity
Connector Terminal
B84 3 Ground Not existed
Air levelizer control module
—Voltage
Connector Terminal
B84 3 Ground 0 V
Air compressor relay —Continuity
Connector Terminal
E116 1 Ground Existed
Air compressor relay Continuity
Te r m i n a l
12Existed
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

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-78
< DTC/CIRCUIT DIAGNOSIS >[AIR LEVELIZER CONTROL SYSTEM]
C1804 VHCL HEIGHT ADJ UP
Is the inspection result normal?
YES >> GO TO 4.
NO >> Repair or replace damaged part.
4.CHECK AIR COMPRESSOR
RELAY OUTPUT CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect air compressor connector.
3. Check continuity between air compressor relay harness connector and air compressor harness connector.
4. Check continuity between air compressor relay harness connector and ground.
Are the inspection results normal?
YES >> GO TO 5.
NO >> Repair or replace damaged part.
5.CHECK AIR COMPRESSOR GROUND
Check continuity between air compressor harness connector and ground.
Are the inspection results normal?
YES >> GO TO 6.
NO >> Repair or replace damaged part.
6.CHECK AIR COMPRESSOR RELAY
Check the air compressor relay. Refer to SCS-79, "
Component Inspection (Air Compressor Relay)".
Is the inspection result normal?
YES >> GO TO 7.
NO >> Replace the air compressor relay.
7.CHECK AIR COMPRESSOR
Check the air compressor. Refer to SCS-79, "
Component Inspection (Air Compressor)".
Is the inspection result normal?
YES >> GO TO 8.
NO >> Replace the air compressor. Refer to SCS-95, "
Removal and Installation".
8.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
Is the inspection result normal?
YES >> 1. Perform “STANDARD VEHICLE HEIGHT SETTING”. Refer to SCS-67, "Work Procedure".
2. If DTC is detected, replace the air levelizer control module. Refer to SCS-94, "
Removal and
Installation".
Air compressor relay
—Voltage
Connector Terminal
E116 5 Ground Battery voltage
Air compressor rela y Air compressor
Continuity
Connector Terminal Connector Terminal
E116 3 C12 1 Existed
Air compressor relay —Continuity
Connector Terminal
E116 3 Ground Not existed
Air compressor —Continuity
Connector Terminal
C12 2 Ground Existed
Revision: 2010 May2011 QX56

C1804 VHCL HEIGHT ADJ UPSCS-79
< DTC/CIRCUIT DIAGNOSIS > [AIR LEVELIZER CONTROL SYSTEM]
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NO >> Repair or replace damaged part.
Component Inspection (A ir Compressor Relay)INFOID:0000000006256072
1.CHECK AIR COMPRESSOR RELAY
1. Remove the air compressor relay. Refer to SCS-50, "
Component Parts Location".
2. Apply 12 V direct current between air compressor relay terminals 1 and 2. CAUTION:
 Never make the terminals short.
 Connect the fuse between the term inals when applying the voltage.
3. Check continuity between air compressor relay terminals 3 and 5.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Replace the air compressor relay. Refer to SCS-50, "
Component Parts Location".
Component Inspection (Air Compressor)INFOID:0000000006256073
CAUTION:
Keep the inside of air compressor free of dust.
1.CHECK AIR COMPRESSOR
1. Remove the air compressor. Refer to SCS-95, "
Removal and Installation".
2. Apply 12 V direct current between air compressor terminals 1 and 2. CAUTION:
 Never make the terminals short.
 Connect the fuse between the term inals when applying the voltage.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Replace the air compressor. Refer to SCS-95, "
Removal and Installation".
(+) (fuse) (−)
Condition Continuity
Air compressor relay
Te r m i n a l
2 1 Apply 12 V direct current between terminals 2 and 1. Existed
— — Does not apply 12 V direct current between terminals 2 and 1. Not existed
(+) (fuse) ( −)
Condition Status
Air compressor
Te r m i n a l
1 2 Apply 12 V direct current between terminals 1 and 2. Air flows from air exhaust holes.
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