2008 INFINITI QX56 height

SCS-22
< COMPONENT DIAGNOSIS >
HEIGHT SENSOR SIGNAL CIRCUIT
HEIGHT SENSOR SIGNAL CIRCUIT
DescriptionINFOID:0000000001731990
Supplies vehicle height input to the suspension control unit.
Component Function CheckINFOID:0000000001731991
1.CHECK HEIGHT SENSOR OPERATION
CONSULT-III
1. Select "HEIGT SEN" of AIR LEVELIZER data monitor test item.
2. While monitoring test item, add or take away weight from the rear of the vehi cle. Check that the voltage
value changes with vehicle height.
Is the HEIGHT SEN data monitor responding normally?
YES >> Height sensor is operating normally.
NO >> Refer to SCS-22, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000001731992
1.CHECK HEIGHT SENSOR POWER AND GROUND SUPPLY
Check height sensor power and ground supply. Refer to SCS-18, "
HEIGHT SENSOR : Diagnosis Procedure"
Are the inspection results normal?
YES >> GO TO 2.
NO >> Repair harness or connector.
2.CHECK HEIGHT SENSOR SIGNAL CIRCUIT
1. Disconnect suspension control unit connector B3 and height sensor connector C8.
2. Check continuity between suspension control unit connector B3 (A) terminal 3 and height sensor connector C8 (B) terminal 2.
3. Check continuity between display unit harness connector B3 (A) terminal 3 and ground.
Are the continuity results as specified?
YES >> Replace the height sensor. Refer to RSU-26, "Removal and Installation"
NO >> Repair harness or connector.HEIGHT SEN : Voltage changes with vehicle height
AB
Continuity
Connector Terminal Connector Terminal
B33C82 Yes
A —Continuity
Connector Terminal
B3 3Ground No
ALEIA0035GB
Revision: March 2010 2008 QX56

EXHAUST VALVE SOLENOID CIRCUITSCS-23
< COMPONENT DIAGNOSIS >
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EXHAUST VALVE SOLENOID CIRCUIT
DescriptionINFOID:0000000001731993
Receives exhaust valve solenoid signal from suspension control unit. When activated, the exhaust valve sole-
noid releases air pressure from the suspension control system.
Component Function CheckINFOID:0000000001731994
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, "
Diagnosis Procedure"
Diagnosis ProcedureINFOID:0000000001731995
1.CHECK EXHAUST VALVE SOLENOID SIGNAL
CONSULT-III
1. Connect suspension control unit connector B3.
2. Turn ignition switch ON.
3. Select "EXHAUST SOLENOID" of AIR LEVELIZER active test
items.
4. While test item is operating, check signal between suspension
air compressor connector C9 terminal 2 and ground.
Is battery voltage present?
YES >> GO TO 3.
NO >> GO TO 2.
2.CHECK CONTINUITY OF EXHAU ST VALVE SOLENOID CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect suspension control unit connector B3 and suspen- sion air compressor connector C9.
3. Check continuity between suspension control unit connector B3
(A) terminal 9 and suspension air compressor connector C9 (B)
terminal 2.ON : Air vents and vehicle ride height lowers
OFF : No air vents and vehicle ride height remains constant
(+)
(-)Voltage
Connector Terminal
C9 2Ground Battery voltage
ALEIA0036GB
AB
Continuity
Connector Terminal Connector Terminal
B39C 92 Y es
ALEIA0037GB
Revision: March 2010 2008 QX56

SUSPENSION CONTROL UNITSCS-27
< ECU DIAGNOSIS >
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ECU DIAGNOSIS
SUSPENSION CONTROL UNIT
Reference ValueINFOID:0000000001731999
TERMINAL LAYOUT
PHYSICAL VALUES
ALNIA0660GB
Te r m i n a l
(Wire color) Description
ConditionReference value
(Approx.)
+ – Signal nameInput/
Output
1
(V) Ground Compressor relay output Output Ignition
switch
ON Air levelizer ra
ising vehicle
ride height Battery voltage
3
(W) Ground Height sensor input
InputIgnition
switch ON —
0.2V - 4.8V
5
(R) Ground VREF output (height sen-
sor) OutputIgnition
switch ON —5
V
6
(G/R) Ground IGN power supply
InputIgnition
switch
ON or
START —
Battery voltage
7
(W/L) Ground BAT power supply
InputIgnition
switch
OFF —
Battery voltage
8
(G/W) Ground Diagnostic K-line Input/
Output ——
—
9
(SB) Ground Exhaust valve output Output Ignition
switch ON Air levelizer lo
wering vehi-
cle ride height (venting) Battery voltage
10
(BR) Ground Warning lamp output Output Ignition
switch ON Warning lamp ON
0V
Warning lamp OFF Battery voltage
14
(L) Ground Height sensor ground Output Ignition
switch
ON —
Less than 0.2V
15
(BR/W) Ground Generator input
InputIgnition
switch ON Charge light ON
0V
Charge light OFF Battery voltage
16
(B) Ground Suspension control unit
ground InputIgnition
switch ON —
Less than 0.2V
Revision: March 2010 2008 QX56

SUSPENSION CONTROL UNITSCS-33
< ECU DIAGNOSIS >
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DTC IndexINFOID:0000000001732001
Self-diagnosis results display item
ALEIA0043GB
CONSULT-III display MalfunctionReference page
Vehicle height sensor [C1801] Vehicle height sensor voltage is less than 0.2V or greater than
4.8V for more than 60 seconds. SCS-9,
"DiagnosisProcedure"
Revision: March 2010
2008 QX56

SCS-34
< ECU DIAGNOSIS >
SUSPENSION CONTROL UNIT
Compressor relay [C1802]• Driving transistor for compre
ssor relay is OFF and monitor
voltage continues at a high level for more than 10 seconds.
• Driving transistor for compressor relay is ON and monitor volt-
age continues at a low level for more than 5 seconds. SCS-10, "DiagnosisProcedure"
Exhaust solenoid [C1803]
• Driving transistor for exhaust valve solenoid is OFF and mon-
itor voltage continues at a high level for more than 10 seconds.
• Driving transistor for exhaust valve solenoid is ON and monitor voltage continues at a low level for more than 5 secondsl. SCS-11, "DiagnosisProcedure"
Vehicle height adjusting malfunction
(compressor)[C1804]
Continuous compressor relay ON time is more than 120 sec-
onds. SCS-12,
"DiagnosisProcedure"
Vehicle height adjusting malfunction
(exhaust solenoid)[C1805]Continuous exhaust valve solenoid ON time is more than 120
seconds. SCS-13,
"DiagnosisProcedure"
Vehicle height sensor locking mal-
function [C1806]Output sensor voltage variation
±0.02V is more than 100 sec-
onds when vehicle height range is normal. SCS-14, "Diagnosis Pro-
cedure"
Sensor 5V malfunction [C1807]
Sensor reference voltage is less than 0.8V or more than 6V for
20 seconds. SCS-15, "DiagnosisProcedure"
Integral time malfunction by supply-
ing air [C1808]A suspension air compressor ON request has been in effect for
180 seconds and the suspension air compressor has not activat-
ed during that time. SCS-16,
"DiagnosisProcedure"
Revision: March 2010
2008 QX56

SUSPENSION CONTROL SYSTEMSCS-35
< SYMPTOM DIAGNOSIS >
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SYMPTOM DIAGNOSIS
SUSPENSION CONTROL SYSTEM
Symptom TableINFOID:0000000001732002
AIR LEVELIZER
Symptom Possible causeReference page
Inoperative • Suspension control unit
• Compressor motor relay
• Suspension air compressorSCS-36, "
Diagnosis
Procedure"
System does not raise• Suspension control unit
• Height sensor
• Compressor motor relay
• Suspension air compressor
• Leak in system
• Restriction in systemSCS-37, "Diagnosis
Procedure"
System does not lower
• Suspension control unit
• Height sensor
• Compressor motor relay
• Suspension air compressor
• Restriction in systemSCS-38, "Diagnosis
Procedure"
CK SUSP indicator lamp
always ON with key ON • CK SUSP indicator lamp control circuit
• Suspension control unit SCS-25, "Descrip-
tion"
Revision: March 2010
2008 QX56

SCS-36
< SYMPTOM DIAGNOSIS >
SUSPENSION CONTROL SYSTEM INOPERATIVE
SUSPENSION CONTROL SYSTEM INOPERATIVE
DescriptionINFOID:0000000001732003
The suspension control system does not activate. It does not raise or lower the vehicle in response to ride
height changes.
Diagnosis ProcedureINFOID:0000000001732004
1.SUSPENSION CONTROL UNIT PO WER AND GROUND INSPECTION
Check the suspension control unit power and ground supply. Refer to SCS-17, "
SUSPENSION CONTROL
UNIT : Diagnosis Procedure".
Does the suspension control unit power and ground pass inspection?
YES >> GO TO 2
NO >> Repair or replace the malfunctioning part.
2.CHECK HEIGHT SENSOR SIGNAL INPUT
CONSULT-III DATA MONITOR
1. Turn ignition switch ON.
2. Select "HEIGT SEN" of AI R LEVELIZER data monitor item.
3. Check the monitor status.
Is the height sensor voltage normal?
YES >> GO TO 3
NO >> Check height sensor signal circuit. Refer to SCS-22, "
Diagnosis Procedure" .
3.CHECK GENERATOR "L" CIRCUIT SIGNAL
CONSULT-III DATA MONITOR
1. Start the engine.
2. Select "ACG L" of AIR LE VELIZER data monitor item.
3. Check the monitor status.
Is the generator "L" signal operating normally?
YES >> GO TO 4.
NO >> Check generator L circuit. Refer to CHG-14, "
Diagnosis Procedure"
4.SUSPENSION AIR COMPRESSOR POWER AND GROUND INSPECTION
Check the suspension air compressor power and ground supply. Refer to SCS-17, "
SUSPENSION AIR COM-
PRESSOR : Diagnosis Procedure".
Does the suspension air compressor power and ground pass inspection?
YES >> System is operating normally.
NO >> Repair or replace the malfunctioning part. HEIGT SEN
: 0.2V - 4.8V
ACG L: OFF with charge light OFF
: ON with charge light ON
Revision: March 2010
2008 QX56

SUSPENSION CONTROL SYSTEM DOES NOT RAISE
SCS-37
< SYMPTOM DIAGNOSIS >
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SUSPENSION CONTROL SYST EM DOES NOT RAISE
DescriptionINFOID:0000000001732005
The suspension control system does not raise the vehicle in accordance with ride height changes.
Diagnosis ProcedureINFOID:0000000001732006
1.SUSPENSION CONTROL UNIT PO WER AND GROUND INSPECTION
Check the suspension control unit power and ground supply. Refer to SCS-17, "
SUSPENSION CONTROL
UNIT : Diagnosis Procedure".
Does the suspension control uni t power and ground pass inspection?
YES >> GO TO 2
NO >> Repair or replace the malfunctioning part.
2.CHECK HEIGHT SENSOR SIGNAL INPUT
CONSULT-III DATA MONITOR
1. Turn ignition ON.
2. Select "HEIGT SEN" of AI R LEVELIZER data monitor item.
3. Check the monitor status.
Is the height sensor voltage normal?
YES >> GO TO 3
NO >> Check height sensor signal circuit. Refer to SCS-22, "
Diagnosis Procedure" .
3.SUSPENSION AIR COMPRESSOR POWER AND GROUND INSPECTION
Check the suspension air compressor power and ground supply. Refer to SCS-17, "
SUSPENSION AIR COM-
PRESSOR : Diagnosis Procedure".
Does the suspension air compress or power and ground pass inspection?
YES >> Inspect for a weak compressor, leak or restriction in the system. Repair or replace malfunctioning
part.
NO >> Repair or replace the malfunctioning part. HEIGT SEN
: 0.2V - 4.8V
Revision: March 2010 2008 QX56