2008 INFINITI QX56 suspension

SCS-12
< COMPONENT DIAGNOSIS >
C1804 HEIGHT ADJUSTING MALFUNCTION (COMPRESSOR)
C1804 HEIGHT ADJUSTING MA LFUNCTION (COMPRESSOR)
DescriptionINFOID:0000000001731969
The compressor motor relay is controlled by the sus pension control unit. The suspension control unit supplies
voltage to the coil side of the relay to activate it. T he compressor motor relay, when activated, supplies power
to the suspension air compressor.
DTC LogicINFOID:0000000001731970
DTC DETECTION LOGIC
Diagnosis ProcedureINFOID:0000000001731971
1.CHECK COMPRESSOR MOTOR RELAY OPERATION
CAUTION:
The "COMPRESSOR" active test will remain ON until it is turned off using CONSULT-III. Allowing the
compressor to run for an extended period of time may cause damage to the air levelizer system com-
ponents due to excessive air pressure.
CONSULT-III
1. Turn ignition ON.
2. Select "COMPRESSOR" of AIR LEVELIZER active test items.
3. While operating test item, check that the suspension air compressor turns ON.
Does the suspension air compressor operate properly?
YES >> Compressor motor relay and suspension air compressor are operating normally.
NO >> Refer to SCS-20, "
Diagnosis Procedure"
DTCDisplay contents of CON-
SULT-III Diagnostic item is detected when ...
Probable malfunction location
C1804 VEHICLE HEIGHT AD-
JUSTING MALFUNC-
TION (COMPRESSOR) Continuous compressor relay ON time is more
than 120 seconds.
Compressor motor relay. Refer to
SCS-20,
"Component Function Check"
ON : Compressor turns ON
OFF : Compressor turns OFF
Revision: March 2010 2008 QX56

C1805 HEIGHT ADJUSTING MALFUNCTION (EXH SOLENOID)
SCS-13
< COMPONENT DIAGNOSIS >
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C1805 HEIGHT ADJUSTING MALF UNCTION (EXH SOLENOID)
DescriptionINFOID:0000000001731972
The exhaust valve solenoid controls the vent function of the suspensi on control system. The exhaust valve
solenoid is built into the suspension air compressor. The suspension control unit supplies voltage to the
exhaust valve solenoid to activate it.
DTC LogicINFOID:0000000001731973
DTC DETECTION LOGIC
Diagnosis ProcedureINFOID:0000000001731974
1.CHECK EXHAUST SOLENOID OPERATION
CAUTION:
While operating this active test, the suspension control system wil l vent air pressure and the vehicle
ride height will lower. Ensure th e area around the vehicle is free from obstructions before beginning
test.
CONSULT-III
1. Ensure the suspension control system has air pressure and is not drooping in the rear.
2. Select "EXHAUST SOLENOID" of AIR LEVELIZER active test items.
3. While operating test item, check that the exhaust va lve solenoid opens to vent air from the system. The
vehicle should lower when the exhaust valve solenoid is activated.
Does the system vent properly?
YES >> Exhaust valve solenoid is operating normally.
NO >> Refer to SCS-23, "
Description"
DTCDisplay contents of CON-
SULT-III Diagnostic item is detected when ...
Probable malfunction location
C1805 VEHICLE HEIGHT AD-
JUSTING MALFUNC-
TION (EXHAUST
SOLENOID) Continuous exhaust valve solenoid ON time is
more than 120 seconds.
Short to power in the exhaust valve solenoid
control circuit. Refer to
SCS-23, "
Component
Function Check"
ON : Air vents and vehicle ride height lowers
OFF : No air vents and vehicle ride height remains constant
Revision: March 2010 2008 QX56

SCS-14
< COMPONENT DIAGNOSIS >
C1806 VEHICLE HEIGHT SENSOR LOCKING MALFUNCTION
C1806 VEHICLE HEIGHT SENSOR LOCKING MALFUNCTION
DescriptionINFOID:0000000001731975
The vehicle height sensor operates on a 5 volt referenc e signal from the suspension control unit. The suspen-
sion control unit also provides ground to the height sensor.
DTC LogicINFOID:0000000001731976
DTC DETECTION LOGIC
Diagnosis ProcedureINFOID:0000000001731977
1.CHECK HEIGHT SENSOR OPERATION
CONSULT-III
1. Turn ignition switch ON
2. Select "HEIGT SEN" of AIR LEVELIZER data monitor test item.
Is the HEIGHT SEN voltage within the given range?
YES >> Height sensor is operating normally.
NO >> Refer to SCS-22, "
Diagnosis Procedure".
DTCDisplay contents of CON-
SULT-III Diagnostic item is detected when ...
Probable malfunction location
C1806 VEHICLE HEIGHT SEN-
SOR LOCKING MAL-
FUNCTION Output sensor voltage variation
±0.02V is more
than 100 seconds when vehicle height range is
normal. • Height sensor power/ground supply. Refer to
SCS-18, "
HEIGHT SENSOR : Diagnosis
Procedure"
• Charging system malfunction. Refer to CHG-
10, "Inspection Procedure"
HEIGHT SEN : 0.2V - 4.8V with no more than ± 0.02V
variation
Revision: March 2010 2008 QX56

C1807 SENSOR 5V MALFUNCTIONSCS-15
< COMPONENT DIAGNOSIS >
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C1807 SENSOR 5V MALFUNCTION
DescriptionINFOID:0000000001731978
The vehicle height sensor operates on a 5 volt referenc e signal from the suspension control unit. The suspen-
sion control unit also provides ground to the height sensor.
DTC LogicINFOID:0000000001731979
DTC DETECTION LOGIC
Diagnosis ProcedureINFOID:0000000001731980
1.POWER SUPPLY CIRCUIT CHECK
1. Disconnect height sensor connector C8.
2. Turn the ignition switch ON.
3. Check voltage between the height sensor connector C8 terminal 1 and ground.
Is 5V present?
YES >> System is working normally.
NO >> Check harness or connector for open or short. If OK, replace the suspension control unit. Refer to RSU-25, "
Removal and Installation"
DTCDisplay contents of CON-
SULT-III Diagnostic item is detected when ...
Probable malfunction location
C1807 SENSOR 5V MALFUNC-
TION Sensor reference voltage is less than 0.8V or
more than 6V for 20 seconds. • Height sensor power/ground supply. Refer to
SCS-18, "
HEIGHT SENSOR : Diagnosis
Procedure"
• Charging system malfunction. Refer to CHG-
10, "Inspection Procedure"
(+)
(-) Voltage
Connector Terminal
C8 1 Ground 5V
ALEIA0026GB
Revision: March 2010 2008 QX56

SCS-16
< COMPONENT DIAGNOSIS >
C1808 INTEGRAL TIME MALFUNCTION SUPPLYING AIR
C1808 INTEGRAL TIME MALFUNCTION SUPPLYING AIR
DescriptionINFOID:0000000001731981
The suspension air compressor is supplied power by the compressor motor relay. The suspension control unit
supplies power to the compressor motor relay in order to activate the relay and subsequently activate the sus-
pension air compressor.
DTC LogicINFOID:0000000001731982
DTC DETECTION LOGIC
Diagnosis ProcedureINFOID:0000000001731983
1.CHECK COMPRESSOR MOTOR RELAY OPERATION
CAUTION:
The "COMPRESSOR" active test will remain ON until it is turned off using CONSULT-III. Allowing the
compressor to run for an extended period of time may cause damage to the air levelizer system com-
ponents due to excessive air pressure.
CONSULT-III
1. Turn ignition ON.
2. Select "COMPRESSOR" of AIR LEVELIZER active test items.
3. While operating test item, check that the suspension air compressor turns ON.
Does the suspension air compressor operate properly?
YES >> Compressor motor relay and suspension air compressor are operating normally.
NO >> Refer to SCS-20, "
Diagnosis Procedure"
DTCDisplay contents of CON-
SULT-III Diagnostic item is detected when ...
Probable malfunction location
C1808 INTEGRAL TIME MAL-
FUNCTION SUPPLYING
AIR A suspension air compressor ON request has
been in effect for 180 seconds and the suspen-
sion air compressor has not activated during
that time. • Compressor motor relay. Refer to
SCS-20,
"Diagnosis Procedure"
• Suspension air compressor. Refer to SCS-
17, "SUSPENSION AIR COMPRESSOR :
Diagnosis Procedure"
ON : Compressor turns ON
OFF : Compressor turns OFF
Revision: March 2010 2008 QX56

POWER SUPPLY AND GROUND CIRCUITSCS-17
< COMPONENT DIAGNOSIS >
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POWER SUPPLY AND GROUND CIRCUIT
SUSPENSION CONTROL UNIT
SUSPENSION CONTROL UNIT : Diagnosis ProcedureINFOID:0000000001731984
1.CHECK FUSES
Check that the following fuses of the sus pension control unit are not are not blown.
Are the fuses OK?
YES >> GO TO 2
NO >> If fuse is blown, be sure to eliminate cause of malfunction before installing new fuse.
2.POWER SUPPLY CIRCUIT CHECK
1. Disconnect suspension control unit connector B3.
2. Check voltage between the suspension control unit connector B3 and ground.
Are the voltage results as specified?
YES >> GO TO 3
NO >> • Check connector housings for disconnected or loose terminals. • Repair harness or connector.
3.GROUND CIRCUIT CHECK
1. Turn ignition switch OFF.
2. Check continuity between suspension control unit harness con- nector B3 and ground.
Is continuity present?
YES >> Inspection End.
NO >> Repair harness or connector.
SUSPENSION AIR COMPRESSOR
SUSPENSION AIR COMPRESSOR : Diagnosis ProcedureINFOID:0000000001731985
1.CHECK COMPRESSOR MOTOR RELAY OPRATION
CONSULT-III
Unit Terminals Signal name Fuse No.
Suspension control unit 7
Battery power 29
6 Ignition switch ON or START 12
(+)
(-) OFF ACC ON START
Connector Terminal
B3 7Ground
Battery
voltage Battery
voltage Battery
voltage Battery
voltage
6Ground0V 0V Battery
voltage Battery
voltage
ALEIA0027GB
Connector Terminal —Continuity
B3 16Ground Yes
ALEIA0028GB
Revision: March 2010 2008 QX56

SCS-18
< COMPONENT DIAGNOSIS >
POWER SUPPLY AND GROUND CIRCUIT
1. Disconnect the suspension air compressor connector C9.
2. Turn ignition switch ON.
3. Select "COMPRESSOR" under AIR LEVELIZER active testitems.
4. While operating the test item, check voltage at the suspension
air compressor connector C9 terminal 4.
Is battery voltage present?
YES >> GO TO 3.
NO >> GO TO 2.
2.COMPRESSOR MOTOR RELAY POWER SUPPLY CIRCUIT CHECK
1. Turn ignition switch OFF.
2. Disconnect the compressor motor relay connector.
3. Check continuity between compressor motor relay connector E131 (A) terminal 3 and suspension air compressor connector
C9 (B) terminal 4.
4. Check continuity between compressor motor relay connector E131 (A) terminal 3 and ground.
Are the continuity test results as specified?
YES >> Check compressor motor relay. Refer to SCS-20, "Diagnosis Procedure"
NO >> Repair harness or connector.
3.GROUND CIRCUIT CHECK
1. Turn ignition switch OFF.
2. Check continuity between suspension air compressor connector C9 terminals 1 and 3 and ground.
Is continuity present?
YES >> Inspection End.
NO >> Repair harness or connector.
HEIGHT SENSOR
HEIGHT SENSOR : Dia gnosis ProcedureINFOID:0000000001731986
1.POWER SUPPLY CIRCUIT CHECK
(+)
(-)Voltage
Connector Terminal
C9 4Ground Battery Voltage
ALEIA0021GB
AB
Continuity
Connector Terminal Connector Terminal
E131 3 C9 4 Yes
A —Con tin uit y
Connector Terminal
E131 3Ground No
ALEIA0022GB
Connector Terminal —Continuity
C9 1
Ground Yes
3
ALEIA0023GB
Revision: March 2010 2008 QX56

POWER SUPPLY AND GROUND CIRCUITSCS-19
< COMPONENT DIAGNOSIS >
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1. Disconnect height sensor connector C8.
2. Turn the ignition switch ON.
3. Check voltage between the height sensor connector C8 terminal 1 and ground.
Is 5V present?
YES >> GO TO 2
NO >> Check harness or connector for open or short. If OK, replace the suspension control unit. Refer to RSU-25, "
Removal and Installation"
2.GROUND CIRCUIT CHECK
1. Turn ignition switch OFF.
2. Check continuity between height sensor connector C8 terminal 3 and ground.
Is continuity present?
YES >> Ground circuit is OK.
NO >> Repair harness or connector.
(+) (-) Voltage
Connector Terminal
C8 1 Ground 5V
ALEIA0026GB
Connector Terminal —Continuity
C8 3Ground Yes
ALEIA0029GB
Revision: March 2010 2008 QX56