air condition INFINITI QX56 2006 Factory Service Manual

TROUBLE DIAGNOSISRSU-7
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How to Perform Trouble Diagnoses for Quick and Accurate RepairEES001H3
INTRODUCTION
The rear load leveling air suspension system uses an electronic con-
trol unit to control major functions. The control unit accepts input sig-
nals from the height sensor and controls compressor and exhaust
valve operation.
It is much more difficult to diagnose a rear load leveling air suspen-
sion system problem that occurs intermittently rather than continu-
ously. Most intermittent problems are caused by poor electrical
connections or faulty wiring. In this case, careful checking of suspi-
cious circuits may help prevent the replacement of good parts.
Before undertaking actual checks, take just a few minutes to talk with
a customer who approaches with an air suspension system com-
plaint. The customer is a very good source of information on such
problems, especially intermittent ones. Through discussion with the
customer, find out what symptoms are present and under what con-
ditions they occur.
Start your diagnosis by looking for basic mechanical problems first.
This is one of the best ways to troubleshoot concerns on an air sus-
pension system equipped vehicle. Also check related Service Bulle-
tins for information.
CLARIFY CONCERN

A customer's description of a vehicle concern may vary depend-
ing on the individual. It is important to clarify the customer's con-
cern.

Ask the customer about what symptoms are present under what
conditions. Use this information to reproduce the symptom.
SEF233G
SEF234G
SBR339B

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TROUBLE DIAGNOSIS
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Basic InspectionEES001H6
AIR HOSES
1. Check for pinched or damaged air hoses between the suspension air reservoir and each load leveling rear
air suspension shock absorber. Reposition, repair or replace hoses as necessary.
2. Check the air hose connections at the suspension air reservoir and at the shock absorbers for leaks. If connections are leaking, repair or replace hoses as necessary.
POWER SYSTEM TERMINAL LOOSENESS AND BATTERY INSPECTION
Make sure the battery positive cable, negative cable and ground connection are not loose. In addition, make
sure the battery is sufficiently charged.
CK SUSP INDICATOR LAMP INSPECTION
1. Make sure the CK SUSP indicator lamp turns on for approximately 2 seconds when the ignition switch is
turned ON. If it does not, check the combination meter. Refer to DI-5, "
COMBINATION METERS" .
2. Make sure the lamp turns off approximately 2 seconds after the ignition switch is turned ON. If the lamp does not turn off, conduct self-diagnosis of the suspension control unit.
3. After conducting the self-diagnosis, be sure to erase the error memory. Refer to RSU-13, "
CONSULT-II
Function (AIR LEVELIZER)" .
CK SUSP Indicator Lamp TimingEES001H7
X: ON
—: OFF
Control Unit Input/Output Signal StandardEES001H8
ConditionCK SUSP
indicator lamp Remarks
Ignition switch OFF ––
Ignition switch ON X Turns off after approximately 2 seconds.
Te r m i n a l
No. Wire color
Item ConditionVoltage (V)
(Approx.)
1 V Compressor relay output
Ignition switch ON or STARTBattery voltage
3 W Height sensor signal input 0.2V - 4.8V
5 R Reference voltage 5V
6 G/R Ignition power
Battery voltage
7W /LB atte ry p ow er —
8 G/W Diagnostic K-line ——
9 SB Exhaust valve output Ignition switch ON or STARTBattery voltage
10 BR Warning lamp output ——
14 L Height sensor ground ——
15 BR/W Generator L signal input Engine running—
16 B Suspension control unit ground —0V

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TROUBLE DIAGNOSIS
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6. Select the required operation from the "SELECT DIAG MODE"
screen.
For further information, see the CONSULT-II Operation Manual.
SELF-DIAGNOSIS
Description
If an error is detected in the system, perform self-diagnosis as follows:
Operation Procedure
1. Turn ignition switch OFF.
2. Connect CONSULT-II and CONSULT-II CONVERTER to the data link connector.
CAUTION:
If CONSULT-II is used with no connection of CONSULT-II CONVERTER, malfunctions might be
detected in self-diagnosis depending on control unit which carries out CAN communication.
3. Turn ignition switch ON.
4. With the engine running, touch "START (NISSAN BASED VHCL)", "AIR LEVELIZER", "SELF-DIAG RESULTS" in order on the CONSULT-II screen.
CAUTION:
When "START (NISSAN BASED VHCL)" is touched immediately after starting the engine or turning
on the ignition switch, "AIR LEVELIZER" might not be displayed in the "SELECT SYSTEM" screen.
In this case, repeat the operation from step 4.
5. The self-diagnostic results are displayed. (If necessary, the self-diagnostic results can be printed out by touching "COPY".)

When "NO DTC IS DETECTED" is displayed, check the CK SUSP indicator lamp.
6. Conduct the appropriate inspection from the display item list, and repair or replace the malfunctioning component.
7. Start and run the vehicle for approximately 1 minute.
8. Turn ignition switch OFF to prepare for erasing the memory.
9. Start the engine and touch "START (NISSAN BASED VHCL)", "AIR LEVELIZER", "SELF-DIAG RESULTS", "ERASE" in order on the CONSULT-II screen to erase the error memory.
If "AIR LEVELIZER" is not indicated, go to GI-40, "
CONSULT-II Data Link Connector (DLC) Circuit" .
CAUTION:
If the error memory is not erased, re-conduct the operation from step 7.
10. For the final inspection, start and run the vehicle for approximately 1 minute and confirm that the CK SUSP indicator lamp is off.
Display Item List
BCIA0031E
Self-diagnostic item Malfunction detecting condition Check system
Vehicle height sensor
[C1801] Vehicle height sensor voltage is less than 0.2V or greater than
4.8V for more than 60 seconds. Refer to
RSU-18, "
Height
Sensor System Inspection" .
Compressor relay
[C1802] 1. Driving transistor for compressor relay is off and monitor volt-
age continues high level for more than 10 seconds.
2. Driving transistor for compressor relay is on and monitor volt- age continues low level for more than 5 seconds. Refer to
RSU-21, "
Compres-
sor Motor, Compressor
Motor Relay and Circuit
Inspection" .
Exhaust solenoid
[C1803] 1. Driving transistor for exhaust solenoid is off and monitor volt-
age continues high level for more than 10 seconds.
2. Driving transistor for exhaust solenoid is on and monitor volt- age continues low level for more than 5 seconds. Refer to
RSU-19, "
Exhaust
Valve Solenoid System
Inspection" .

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WORK SUPPORT
Operation Procedure
1. After turning OFF the ignition switch, connect CONSULT-II and the CONSULT-II CONVERTER to the data
link connector.
CAUTION:
If CONSULT-II is used with no connection of CONSULT-II CONVERTER, malfunctions might be
detected in self-diagnosis depending on control unit which carries out CAN communication.
2. Touch "START (NISSAN BASED VHCL)", "AIR LEVELIZER", "WORK SUPPORT" in order on the CON- SULT-II screen.
If "AIR LEVELIZER" is not indicated, go to GI-40, "
CONSULT-II Data Link Connector (DLC) Circuit" .
CAUTION:
When "START (NISSAN BASED VHCL)" is touched immediately after starting the engine or turning
on the ignition switch, "AIR LEVELIZER" might not be displayed in the "SELECT SYSTEM" screen.
In this case, repeat the operation from step 2.
3. Select "STANDARD HEIGHT LEVEL", "ADJUST HEIGHT INI" or "CLEAR HEIGHT INI" on the "SELECT WORK ITEM" screen.
NOTE:
Read and perform screen instructions if "STANDARD HEIGHT LEVEL" or "ADJUST HEIGHT INI" is
selected.
4. Touch "START" to begin the desired work support.
Display Item List
Vehicle height adjusting trouble
(compressor)
[C1804] Continuous compressor relay ON time is more than 120 sec-
onds. Refer to
RSU-21, "Compres-
sor Motor, Compressor
Motor Relay and Circuit
Inspection" .
Vehicle height adjusting trouble
(exhaust solenoid)
[C1805] Continuous exhaust solenoid ON time is more than 120 seconds. Refer to
RSU-19, "
Exhaust
Valve Solenoid System
Inspection" .
Vehicle height sensor locking trou-
ble
[C1806] Output sensor voltage variation ±
0.02V is more than 100 hour
when vehicle height range is normal. Refer to
RSU-18, "
Height
Sensor System Inspection" .
Sensor 5V trouble
[C1807] Sensor reference voltage is less than 0.8V or more than 6V for
20 seconds. Refer to
RSU-18, "
Height
Sensor System Inspection" .
Integral time trouble by supplying
air
[C1808] Integral discontinuous time on the compressor is more than 180
seconds. Refer to
RSU-21, "
Compres-
sor Motor, Compressor
Motor Relay and Circuit
Inspection" .
Self-diagnostic item
Malfunction detecting condition Check system
ItemDescription Condition
STANDARD HEIGHT LEVEL Resets the vehicle height to the initialization flag
setting stored in the suspension control unit. Vehicle unladen
RSU-49, "
Wheelarch Height
(Unladen*1 )" , set in a horizontal position and
not moving.
NOTE:
Do not take your eyes off the vehicle while
CONSULT-II is processing.
ADJUST HEIGHT INI Sets the height initialization flag in the suspension
control unit when the control unit has been replaced
or when the initialization flag has been cleared
using the "CLEAR HEIGHT INI" procedure. Vehicle unladen
RSU-49, "
Wheelarch Height
(Unladen*1 )" . Move vehicle forward and
backward approx. 5 m (16.4 ft) and rock vehi-
cle from side to side.
NOTE:
Do not move vehicle while CONSULT-II is pro-
cessing.
CLEAR HEIGHT INI Clears the initialization flag in the suspension con-
trol unit. Vehicle unladen
RSU-49, "
Wheelarch Height
(Unladen*1 )" .

RSU-20
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
Revision: November 20092006 QX56
2. CHECK SYSTEM OPERATION
1. Load vehicle to standard laden condition (with driver, front passenger, 2 passengers in second row seats and no cargo).
2. Conduct active test of "COMPRESSOR" to raise vehicle ride height to +20mm. CAUTION:
The "COMPRESSOR" active test will remain ON until it is turned off using CONSULT-II. Allowing
the compressor to run for an extended period of time may cause damage to air suspension sys-
tem components due to excessive pressure in the air suspension system.
3. Return the rear load leveling air suspension system to normal operating mode.
4. Check self-diagnostic results.
Is code C1805 displayed again?
YES >> GO TO 3.
NO >> Inspection End.
3. CONNECTOR INSPECTION
1. Disconnect suspension control unit connector B3 and suspension air compressor C9.
2. Check the terminals for deformation, disconnection, looseness or damage.
OK or NG
OK >> If code C1805 was retrieved during self-diagnosis, GO TO 4. If code C1803 was retrieved during self-diagnosis, GO TO 6.
NG >> Repair or replace as necessary.
4. AIR HOSE INSPECTION
Inspect for pinched or damaged air hoses between the suspension air reservoir and each load leveling rear air
suspension shock absorber.
OK or NG
OK >> GO TO 5.
NG >> Repair or replace as necessary.
5. EXHAUST VALVE SOLENOID INSPECTION
Apply 12V to suspension air compressor terminal 2 and ground to
suspension air compressor terminal 1.
OK or NG
OK >> GO TO 6.
NG >> Replace the suspension air compressor. Refer to RSU-
43, "REAR LOAD LEVELING AIR SUSPENSION COM-
PRESSOR ASSEMBLY" .
System air pressure should vent.
WEIA0063E

TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMSRSU-21
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6. CHECK EXHAUST VALVE SOLENOID POWER AND GROUND
1. Reconnect the suspension control unit connector.
2. Turn the ignition switch ON.
3. Check voltage between suspension air compressor connector C9 terminal 2 and ground.
4. Turn ignition switch OFF.
5. Check continuity between suspension air compressor connector C9 terminal 1 and ground.
OK or NG
OK >> Replace the suspension control unit. Refer to RSU-47,
"CONTROL UNIT" .
NG >> Repair harness or connector.
Compressor Motor, Compressor Motor Relay and Circuit InspectionEES001HC
INSPECTION PROCEDURE
1. SELF-DIAGNOSIS RESULT CHECK
Check self-diagnosis results.
Is the above displayed in the self-diagnosis display items?
YES >> If code C1802 was retrieved during self-diagnosis, GO TO 3. If code C1804 or C1808 was retrieved during self-diagnosis, GO TO 2.
NO >> Inspection End.
2. CHECK SYSTEM OPERATION
1. Load vehicle to standard laden condition (with driver, front passenger, 2 passengers in second row seats and no cargo).
2. Conduct active test of "EXHAUST SOLENOID" to lower vehicle ride height to -20mm.
3. Return the rear load leveling air suspension system to normal operating mode.
4. Check self-diagnostic results.
Is code C1804 or C1808 displayed again?
YES >> GO TO 3.
NO >> Inspection End. Voltage
: Approx. 12V
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1 - GroundContinuity should exist.
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Self-diagnosis results
C1802
C1804
C1808

REAR SUSPENSION ASSEMBLYRSU-27
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Rear Load Leveling Air Suspension System
On-Vehicle Inspection and ServiceEES001HG
Check all of the component mountings for any excessive looseness, or back lash. Check the components for
any excessive wear, damage, or abnormal conditions. Repair or replace the components as necessary.
SHOCK ABSORBER INSPECTION

Check the shock absorbers for any air leaks or damage, and replace as necessary.

Check the hoses for any air leaks or damage, and replace as necessary.
1. Seat belt latch anchor2. Stabilizer bar bushing3. Stabilizer bar clamp
4. Stabilizer bar 5. Connecting rod6. Front lower link
7. Knuckle 8. Bushing9. Rear lower link
10. Shock absorber 11. Suspension arm12. Lower rubber seat
13. Coil spring 14. Upper rubber seat15. Rear suspension member
16. Spare tire bracket 17. Bound bumper
LEIA0072E
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

RSU-28
REAR SUSPENSION ASSEMBLY
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Wheel Alignment InspectionEES001HH
Rear Wheel Alignment Adjusting Bolts
PRELIMINARY INSPECTION
WARNING:
Always adjust the alignment with the vehicle on a flat surface. Use CONSULT-II “EXHAUST SOLE-
NOID” active test to release the air pressure from the rear load leveling air suspension system.
NOTE:
If alignment is out of specification, inspect and replace any damaged or worn rear suspension parts before
making any adjustments.
1. Check and adjust the wheel alignment with the vehicle under unladen conditions. “Unladen conditions”
means that the fuel, coolant, and lubricant are full; and that the spare tire, jack, hand tools and mats are in
their designated positions.
2. Check the tires for incorrect air pressure and excessive wear.
3. Check the wheels for runout and damage. Refer to WT-5, "
Inspection" .
4. Check the wheel bearing axial end play.
5. Check the shock absorbers. Refer to RSU-27, "
SHOCK ABSORBER INSPECTION" .
6. Check each mounting point of the suspension components for any excessive looseness or damage.
7. Check each link, arm, and the rear suspension member for any damage.
8. Check the vehicle height. Refer to RSU-49, "
Wheelarch Height (Unladen*1 )" .

If vehicle height is not within ± 10 mm (0.39 in) of the specification, perform the control unit initialization
procedure. Refer to RSU-47, "
Initialization Procedure" .
GENERAL INFORMATION AND RECOMMENDATIONS
1. A Four-Wheel Thrust Alignment should be performed.

This type of alignment is recommended for any NISSAN vehicle.

The four-wheel “thrust” process helps ensure that the vehicle is properly aligned and the steering wheel
is centered.

The alignment machine itself should be capable of accepting any NISSAN vehicle.

The alignment machine should be checked to ensure that it is level.
2. Make sure the alignment machine is properly calibrated.

Your alignment machine should be regularly calibrated in order to give correct information.
WEIA0102E
1. Rear lower link adjusting bolt, LH 2. Front lower link adjusting bolt, LH 3. Front lower link adjusting bolt, RH
4. Rear lower link adjusting bolt, RH
Axial end play : 0 mm (0 in)

RSU-34
REAR SUSPENSION MEMBER
Revision: November 20092006 QX56
INSTALLATION
Installation is in the reverse order of removal.

When raising the rear suspension member assembly, use the
locating pins to align the rear suspension member to the vehicle
body.

When installing the upper and lower rubber seats for the rear
coil springs, the arrow embossed on the rubber seats must point
out toward the wheel and tire assembly.

To connect the rear load leveling air suspension hoses, the lock
ring must be fully seated in the fitting. 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.

Perform the final tightening of the nuts and bolts for the links (rubber bushing) under unladen condition
(unladen condition means that the fuel tank, engine coolant and lubricants are at the full specification, and
the spare tire, jack, hand tools, and mats are in their designated positions) with the tires on level ground.

Check the wheel alignment. Refer to RSU-48, "Wheel Alignment" .
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RSU-38
FRONT LOWER LINK
Revision: November 20092006 QX56
FRONT LOWER LINKPFP:55110
Removal and InstallationEES001HL
REMOVAL
1. Remove the wheel and tire assembly using power tool.
2. Use CONSULT-II "EXHAUST SOLENOID" active test to release the air pressure from the rear load level-
ing air suspension system.
3. Remove the shock absorber lower end bolt.
4. Remove the adjusting bolt and nut, and the bolt and nut, from the front lower link and rear suspension member using power
tool.
5. Remove the front lower link pinch bolt and nut on the knuckle side using power tool.
6. Disconnect the front lower link from the knuckle using a soft hammer.
CAUTION:
Do not damage the ball joint with the soft hammer.
7. Remove the front lower link.
INSPECTION AFTER REMOVAL

Check the front lower link and bushing for any deformation, crack, or damage. Replace if necessary.

Check the rubber bushing for damage, cracks and deformation. Replace the front lower link and bushing if
necessary.

Before checking, turn the ball joint at least 10 revolutions so that the ball joint is properly broken in.

Check the ball joint. Replace the front lower link if any of the fol-
lowing conditions exist:
–Ball stud is worn.
–Joint is hard to swing.
–Play in axial direction is excessive.
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LEIA0086E
Swinging force “A” : Refer to RSU-48, "Ball Joint" .
Turning force “B” : Refer to RSU-48, "
Ball Joint" .
Vertical end play “C” : Refer to RSU-48, "
Ball Joint" .
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