service INFINITI QX56 2007 Factory Service Manual

TROUBLE DIAGNOSIS
RSU-11
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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
.
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-11, "
CONSULT-II
Function (AIR LEVELIZER)" .
Chek Suspension Indicator Lamp TimingINFOID:0000000003532661
X: ON
—: OFF
Control Unit Input/Output Signal StandardINFOID:0000000003532662
CONSULT-II Function (AIR LEVELIZER)INFOID:0000000003532663
CONSULT-II can display each diagnostic item using the diagnostic test modes shown following.
CONSULT-II START PROCEDURE
Refer to GI-36, "CONSULT-II Start Procedure".
ConditionCK SUSP
indicator lampRemarks
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/LBattery power —
8 G/W Diagnostic K-line — —
9 SB Exhaust valve output Ignition switch ON or START Battery 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
AIR LEVELIZER
diagnostic modeDescription
WORK SUPPORTSupports inspections and adjustments. Commands are transmitted to the BCM for setting the status
suitable for required operation, input/output signals are received from the BCM and received data is
displayed.
SELF-DIAG RESULTS Displays suspension control unit self-diagnosis results.
DATA MONITOR Displays suspension control unit input/output data in real time.
ACTIVE TEST Operation of electrical loads can be checked by sending drive signal to them.
ECU PART NUMBER Suspension control unit part number can be read.

RSU-12
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
SELF-DIAGNOSIS
Display Item List
WORK SUPPORT
Display Item List
DATA MONITOR
Display Item List
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-14, "
Height
Sensor System Inspection" .
Compressor relay
[C1802]1. Driving transistor for compressor relay is off and monitor
voltage continues high level for more than 10 seconds.
2. Driving transistor for compressor relay is on and monitor
voltage continues low level for more than 5 seconds.Refer to RSU-17, "
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-15, "
Exhaust
Valve Solenoid System In-
spection" .
Vehicle height adjusting trouble
(compressor)
[C1804]Continuous compressor relay ON time is more than 120 seconds.Refer to RSU-17, "
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-15, "
Exhaust
Valve Solenoid System In-
spection" .
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-14, "
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-14, "
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-17, "
Compres-
sor Motor, Compressor Motor
Relay and Circuit Inspec-
tion".
Item Description Condition
STANDARD HEIGHT LEVELResets the vehicle height to the initialization flag set-
ting stored in the suspension control unit.Vehicle unladen RSU-44, "
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 INISets 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-44, "
Wheelarch Height
(Unladen*1)" . Move vehicle forward and back-
ward approx. 5 m (16.4 ft) and rock vehicle from
side to side.
NOTE:
Do not move vehicle while CONSULT-II is pro-
cessing.
CLEAR HEIGHT INIClears the initialization flag in the suspension control
unit.Vehicle unladen RSU-44, "
Wheelarch Height
(Unladen*1)" .

TROUBLE DIAGNOSIS
RSU-13
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X: Applicable
–: Not applicable
ACTIVE TEST
CAUTION:
• Do not perform active test while driving.
Display Item List
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 system com-
ponents due to excessive pressure in the air suspension system.
NOTE:
• "TEST IS STOPPED" is displayed approximately 10 seconds after operation starts for all active test items
except "COMPRESSOR".
• After "TEST IS STOPPED" is displayed, to perform test again, repeat Step 6.
Test ItemData monitor item selection
ALL
SIGNALSSELECTION
FROM MENU
HEIGT SENXX
HEIGT CALCXX
SEN FIX TIME X X
HEIGT INI VAL X X
COMPRESSOR X X
EXH SOLENOID X X
ACG LXX
Test Item Description
COMPRESSOROFF/ON
EXHAUST SOLENOID OFF/ON
WARNING LAMPOFF/ON

RSU-14
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
Height Sensor System InspectionINFOID:0000000003532664
INSPECTION PROCEDURE
1.SELF-DIAGNOSIS RESULT CHECK
Check self-diagnosis results.
Is the above displayed in the self-diagnosis display items?
YES >> GO TO 3.
NO >> GO TO 2.
2.DATA MONITOR CHECK
Conduct data monitor of "HEIGT SEN" to check if the status is normal.
OK or NG
OK >> Inspection End.
NG >> GO TO 3.
3.CONNECTOR INSPECTION
1. Disconnect suspension control unit connector B3 and height sensor C8.
2. Check the terminals for deformation, disconnection, looseness or damage.
OK or NG
OK >> GO TO 4.
NG >> Repair or replace as necessary.
4.CHECK HEIGHT SENSOR POWER
1. Reconnect the suspension control unit connector.
2. Turn the ignition switch ON.
3. Check voltage between height sensor connector C8 terminal 1
and ground.
OK or NG
OK >> GO TO 5.
NG >> Check harness or connector for open or short. If OK,
replace suspension control unit. Refer to RSU-42
.
5.CHECK HEIGHT SENSOR GROUND
1. Turn ignition switch OFF.
Self-diagnosis results
C1801
C1806
C1807
HEIGT SEN 0.2V - 4.8V
Voltage : Approx. 5V
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TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
RSU-15
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2. Check continuity between height sensor connector C8 terminal
3 and ground.
OK or NG
OK >> GO TO 6.
NG >> Repair harness or connector.
6.CHECK HEIGHT SENSOR SIGNAL CIRCUIT
1. Disconnect suspension control unit connector.
2. Check continuity between height sensor connector C8 terminal
2 and suspension control unit connector B3 terminal 3.
3. Check continuity between height sensor connector C8 terminal
2 and ground.
OK or NG
OK >> Replace the height sensor. Refer to RSU-40.
NG >> Repair harness or connector.
Exhaust Valve Solenoid System InspectionINFOID:0000000003532665
INSPECTION PROCEDURE
1.SELF-DIAGNOSIS RESULT CHECK
Check self-diagnosis results.
Is the above displayed in the self-diagnosis display items?
YES >> If code C1803 was retrieved during self-diagnosis, GO TO 3. If code C1805 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 "COMPRESSOR" to raise vehicle ride height to +20mm.
CAUTION:3 - Ground Continuity should exist.
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2 - 3 Continuity should exist.
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2 - Ground Continuity should not exist.
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Self-diagnosis results
C1803
C1805

RSU-16
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
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-
38.
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.System air pressure should vent.
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Voltage : Approx. 12V
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TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
RSU-17
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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-42.
NG >> Repair harness or connector.
Compressor Motor, Compressor Motor Relay and Circuit InspectionINFOID:0000000003532666
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.
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 C1804 or C1808 was retrieved during self-diagnosis, GO TO 4. If code C1802 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.SUSPENSION AIR COMPRESSOR INSPECTION1 - Ground Continuity should exist.
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Self-diagnosis results
C1802
C1804
C1808

RSU-18
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
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-
38.
6.CHECK SUSPENSION AIR COMPRESSOR POWER AND GROUND
1. Connect suspension control unit connector B3.
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-42.
NG >> Repair harness or connector.System air pressure should vent.
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Voltage : Approx. 12V
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1 - Ground Continuity should exist.
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TROUBLE DIAGNOSES FOR SYMPTOMS
RSU-19
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TROUBLE DIAGNOSES FOR SYMPTOMS
Load Leveling Rear Air Suspension System Does Not OperateINFOID:0000000003532667
1.CHECK WARNING LAMP ACTIVATION
Make sure warning lamp remains off while driving.
OK or NG
OK >> GO TO 2.
NG >> Carry out self-diagnosis. Refer to RSU-11, "
CONSULT-II Function (AIR LEVELIZER)" .
2.CHECK FUSES AND FUSIBLE LINK
Check that the following fuses and fusible link are not blown.
OK or NG
OK >> GO TO 3.
NG >> If fuse or fusible link is blown, be sure to eliminate cause of malfunction before installing new fuse
or fusible link.
3.CHECK SUSPENSION CONTROL UNIT POWER AND GROUND
1. Turn the ignition switch ON.
2. Check voltage between suspension control unit connector B3
terminal 6 and ground and between suspension control unit con-
nector B3 terminal 7 and ground.
3. Turn the ignition switch OFF.
4. Check continuity between suspension control unit connector B3
terminal 16 and ground.
OK or NG
OK >> GO TO 4.
NG >> Repair harness or connector.
4.CHECK GENERATOR SIGNAL INPUT
1. Start the engine.
Unit Terminals Signal name Fuse and fusible link No.
Suspension control unit6 Ignition switch ON or START 12 (10A)
7
Battery power29 (10A)
Compressor motor relay 5 g (30A)
Combination meter24 Ignition switch ON or START 14 (10A)
8 Battery power 19 (10A)
Voltage : Approx. 12V
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16 - Ground Continuity should exist.
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RSU-20
< SERVICE INFORMATION >
TROUBLE DIAGNOSES FOR SYMPTOMS
2. Check voltage between suspension control unit connector B3
terminal 15 and ground.
OK or NG
OK >> Replace the suspension control unit. Refer to RSU-42.
NG >> Repair the circuit.
Chek Suspension Indicator Lamp Stays On When Ignition Switch Is Turned On
INFOID:0000000003532668
1.CARRY OUT SELF-DIAGNOSIS
Carry out self-diagnosis. Refer to RSU-11, "
CONSULT-II Function (AIR LEVELIZER)".
Are malfunctions detected in self-diagnosis?
YES >> Refer to RSU-11, "CONSULT-II Function (AIR LEVELIZER)" .
NO >> Refer to DI-26
. Voltage : Approx. 12V
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