2009 INFINITI QX56 air suspension

REAR LOAD LEVELING AIR SUSPENSION COMPRESSOR ASSEMBLY
RSU-25
< REMOVAL AND INSTALLATION >
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M A
B
RSU
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5. Remove the four bolts that mount the rear load leveling air sus- pension compressor assembly to the underbody.
INSTALLATION
Installation is in the reverse order of removal.
 To connect the rear load leveling air suspension hoses, the lockring must be fully seated in the fitt ing. Insert the hose (B) into the
lock ring (A) until the lock ring (A) is touching the hose (B) as
shown. Pull on the hose to check that it is securely inserted.
LEIA0090E
LEIA0078E
Revision: December 20092009 QX56

RSU-26
< REMOVAL AND INSTALLATION >
CONTROL UNIT
CONTROL UNIT
Removal and InstallationINFOID:0000000003772300
REMOVAL
1. Remove the rear LH interior trim panel. Refer to INT-14, "Removal and Installation" .
2. Disconnect the battery negative terminal.
3. Disconnect the suspension control unit electrical connector.
4. Remove the two bolts and remove the suspension control unit.
INSTALLATION
Installation is in the reverse order of removal.
Initialization ProcedureINFOID:0000000003772301
1. If control unit has been replaced, proceed to step 2. If control unit has not been replaced, use CONSULT-
III “CLEAR HEIGHT INI” work support function to clear initialization flag and value. The CK SUSP warning
lamp should illuminate. Using CONSULT-III “EXHAUST SOLENOID” active test, release the air pressure
from the rear load leveling air suspension system.
2. Roll vehicle forward and backward.
3. Use CONSULT-III “ADJUST HEIGHT INI” work support function to set initialization condition.
4. Confirm that CK SUSP warning lamp is OFF.
LEIA0100E
Suspension control unit bolts : 6 N·m (0.6 kg-m, 53 in-lb)
Revision: December 20092009 QX56

HEIGHT SENSORRSU-27
< REMOVAL AND INSTALLATION >
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HEIGHT SENSOR
Removal and InstallationINFOID:0000000003772302
Rear Load Leveling Air Suspension System
REMOVAL
1. Use CONSULT-III “EXHAUST SOLENOID ” active test to release the air pressure from the rear load level-
ing air suspension system.
2. Disconnect the electrical connector for the height sensor.
3. Remove the two height sensor bolts and height sensor arm bracket bolt.
4. Remove the height sensor.
INSTALLATION
Installation is in the reverse order of removal.
AWEIA0054GB
1. Rear load leveling air suspension hose, RH 2. Shock absorber, RH 3. Height sensor
4. Rear load leveling air suspension hose, LH 5. Shock absorber, LH 6. Rear load leveling air suspension
compressor assembly
Front
LEIA0080E
Revision: December 20092009 QX56

RSU-30
< SERVICE DATA AND SPECIFICATIONS (SDS)
SERVICE DATA AND SPECIFICATIONS (SDS)
Wheelarch Height (Unladen*
1)INFOID:0000000003772305
Unit: mm (in)
*1: Fuel, engine coolant and engine oil full. Spare tire, jack, hand tools and mats in designated positions.
*2: Verify the vehicle height. If vehicle height is not within ± 10 mm (0.39 in) of the specification, perform the control unit initialization pro-
cedure. Refer to RSU-26, "Initialization Procedure"
.
Suspension type
Air leveling*
2
Applied model2WD 4WD
Front wheelarch height (Hf) 920
(36.22) 937
(36.89)
Rear wheelarch height (Hr) 917
(36.10) 937
(36.89)
LEIA0085E
Revision: December 20092009 QX56

SCS-1
SUSPENSION
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SECTION SCS
A
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O PCONTENTS
SUSPENSION CONTROL SYSTEM
BASIC INSPECTION ....... .............................3
DIAGNOSIS AND REPAIR WORKFLOW ..... .....3
Work Flow ........................................................... ......3
FUNCTION DIAGNOSIS ...............................5
SUSPENSION CONTROL SYSTEM .............. .....5
System Diagram .................................................. ......5
System Description ...................................................5
Component Parts Location ........................................6
Component Description .............................................6
DIAGNOSIS SYSTEM (SUSPENSION CON-
TROL UNIT) .........................................................
7
CONSULT-III Function ..............................................7
COMPONENT DIAGNOSIS ..........................9
C1801 VEHICLE HEIGHT SENSOR .............. .....9
Description .......................................................... ......9
DTC Logic .................................................................9
Diagnosis Procedure ................................................9
C1802 COMPRESSOR RELAY .........................10
Description ..............................................................10
DTC Logic ...............................................................10
Diagnosis Procedure ..............................................10
C1803 EXHAUST SOLENOID ...........................11
Description ..............................................................11
DTC Logic ...............................................................11
Diagnosis Procedure ..............................................11
C1804 HEIGHT ADJUSTING MALFUNCTION
(COMPRESSOR) ............................................ ....
12
Description .......................................................... ....12
DTC Logic ...............................................................12
Diagnosis Procedure ..............................................12
C1805 HEIGHT ADJUSTING MALFUNCTION
(EXH SOLENOID) ..............................................
13
Description ........................................................... ....13
DTC Logic ................................................................13
Diagnosis Procedure ..............................................13
C1806 VEHICLE HEIGHT SENSOR LOCK-
ING MALFUNCTION .........................................
14
Description ........................................................... ....14
DTC Logic ................................................................14
Diagnosis Procedure ...............................................14
C1807 SENSOR 5V MALFUNCTION ...............15
Description ...............................................................15
DTC Logic ................................................................15
Diagnosis Procedure ..............................................15
C1808 INTEGRAL TIME MALFUNCTION
SUPPLYING AIR ...............................................
16
Description ...............................................................16
DTC Logic ................................................................16
Diagnosis Procedure ..............................................16
POWER SUPPLY AND GROUND CIRCUIT ....17
SUSPENSION CONTROL UNIT ................................17
SUSPENSION CONTROL UNI T : Diagnosis Pro-
cedure .................................................................. ....
17
SUSPENSION AIR COMPRESSOR ..........................17
SUSPENSION AIR COMPRESSOR : Diagnosis
Procedure ............................................................ ....
17
HEIGHT SENSOR .................................................. ....18
HEIGHT SENSOR : Diagnosis Procedure ..............18
COMPRESSOR MOTOR RELAY .....................20
Description ...............................................................20
Component Function Check ....................................20
Diagnosis Procedure ...............................................20
HEIGHT SENSOR SIGNAL CIRCUIT ...............22
Description ...............................................................22
Component Function Check ....................................22
Diagnosis Procedure ...............................................22
Revision: December 20092009 QX56

SCS-2
EXHAUST VALVE SOLENOID CIRCUIT ..........23
Description ........................................................... ...23
Component Function Check ...................................23
Diagnosis Procedure ..............................................23
CK SUSP WARNING INDICATOR CONTROL
CIRCUIT .............................................................
25
Description ........................................................... ...25
Component Function Check ...................................25
Diagnosis Procedure ..............................................25
ECU DIAGNOSIS ..................................... ...27
SUSPENSION CONTROL UNIT ........................27
Reference Value .................................................. ...27
Wiring Diagram .......................................................28
DTC Index ..............................................................33
SYMPTOM DIAGNOSIS .............................35
SUSPENSION CONTROL SYSTEM .............. ...35
Symptom Table ................................................... ...35
SUSPENSION CONTROL SYSTEM INOPER-
ATIVE .................................................................
36
Description ........................................................... ...36
Diagnosis Procedure ...............................................36
SUSPENSION CONTROL SYSTEM DOES
NOT RAISE ........................................................
37
Description ........................................................... ...37
Diagnosis Procedure ...............................................37
SUSPENSION CONTROL SYSTEM DOES
NOT LOWER .....................................................
38
Description ........................................................... ...38
Diagnosis Procedure ...............................................38
PRECAUTION ............................................39
PRECAUTIONS .............................................. ...39
Precaution for Supplemental Restraint System
(SRS) "AIR BAG" and "SEAT BELT PRE-TEN-
SIONER" .............................................................. ...
39
Precaution for Rear Suspension .............................39
Revision: December 20092009 QX56

SUSPENSION CONTROL SYSTEMSCS-5
< FUNCTION DIAGNOSIS >
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FUNCTION DIAGNOSIS
SUSPENSION CONTROL SYSTEM
System DiagramINFOID:0000000003772307
System DescriptionINFOID:0000000003772308
SUSPENSION CONTROL SYSTEM
The suspension control system consists of the following components
• Suspension control unit
• Compressor motor relay
• Suspension air compressor
• Exhaust valve solenoid (built into suspension air compressor)
• Height sensor
The suspension control unit monitors vehicle ride height as indicated by the height sensor. The suspension
control unit actuates the compressor motor relay to ra ise the vehicle ride height. The suspension control unit
actuates the exhaust valve solenoid to lower the vehicle ride height.
CK SUSP INDICATOR LAMP
The CK SUSP indicator lamp ground is controlled by the suspension control unit. The indicator lamp will come
on for 2 seconds when the ignition switch is turned ON. If the indicator lamp does not turn OFF there is a fault
detected. Refer to SCS-7, "
CONSULT-III Function".
ALEIA0042GB
Revision: December 20092009 QX56

SCS-6
< FUNCTION DIAGNOSIS >
SUSPENSION CONTROL SYSTEM
Component Parts Location
INFOID:0000000003772309
:Front
Component DescriptionINFOID:0000000003772310
1. Suspension control unit B3 (view with upper and lower luggage side finishers
LH removed) 2. Suspension air compressor C9 (view
under vehicle behind LH rear suspen-
sion) 3. Height sensor C8 (view under vehicle
at LH rear suspension)
4. Compressor motor relay E130, E131 (view with battery removed)
ALEIA0044ZZ
Part name Description
Suspension control unit • Monitors height sensor input to determine vehicle height.
• Actuates the compressor motor relay or exhaust valve solenoid to raise or
lower the vehicle accordingly.
• Sends a ground signal to the combination meter to activate the CK SUSP indicator lamp.
Suspension air compressor (with built in exhaust valve
solenoid) • When the compressor is actuated, it pumps air into the system to raise the
rear suspension.
• When the exhaust valve solenoid is actuated, it vents air from the system to lower the rear suspension.
Height sensor Provides vehicle height input to the suspension control unit.
Revision: December 20092009 QX56