air suspension INFINITI QX56 2010 Factory Repair Manual

HEIGHT SENSOR SIGNAL CIRCUITSCS-23
< COMPONENT DIAGNOSIS >
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HEIGHT SENSOR SIGNAL CIRCUIT
DescriptionINFOID:0000000005148181
Supplies vehicle height input to the suspension control unit.
Component Function CheckINFOID:0000000005148182
1.CHECK HEIGHT SENSOR OPERATION
CONSULT-III
1. Select "HEIGT SEN" of AIR L EVELIZER data monitor test item.
2. While monitoring test item, add or take away weight from the rear of the vehicle. 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-23, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000005148183
Regarding Wiring Diagram information, refer to SCS-29, "Wiring Diagram".
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-27, "Removal and Installation".
NO >> Repair harness or connector. HEIGHT SEN : Voltage changes with vehicle height
AB
Continuity
Connector Terminal Connector Terminal
B33C 82 Y es
A —Contin u it y
Connector Terminal
B3 3Ground No
ALEIA0035GB
Revision: April 20092010 QX56

SCS-24
< COMPONENT DIAGNOSIS >
EXHAUST VALVE SOLENOID CIRCUIT
EXHAUST VALVE SOLENOID CIRCUIT
DescriptionINFOID:0000000005148184
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:0000000005148185
1.CHECK EXHAUST SOLENOID OPERATION
CAUTION:
While operating this active test, the suspension control system will vent air pressure and the vehicle
ride height will lower. Ensure th e area around the vehicle is free fr om 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 valve 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-24, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000005148186
Regarding Wiring Diagram information, refer to SCS-29, "Wiring Diagram".
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 EXHA UST VALVE SOLENOID CIRCUIT
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
Revision: April 20092010 QX56

EXHAUST VALVE SOLENOID CIRCUITSCS-25
< COMPONENT DIAGNOSIS >
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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.
4. Check continuity between suspension control unit connector B3 (A) terminal 9 and ground.
Are the continuity test results as specified?
YES >> Replace the suspension control unit. Refer to RSU-26, "Removal and Installation".
NO >> Repair harness or connector.
3.CHECK SUSPENSION AIR COMPRESSOR GROUND
1. Turn ignition switch OFF.
2. Check continuity between suspension air compressor connector C9 terminals 1 and 3 and ground.
Is continuity present?
YES >> Replace the suspension air compressor. Refer to RSU-
24, "Removal and Installation".
NO >> Repair harness or connector.
AB Continuity
Connector Terminal Connector Terminal
B39C 92 Y es
A —Contin u it y
Connector Terminal
B3 9Ground No
ALEIA0037GB
ConnectorTerminal —Continuity
C9 1
Ground Yes
3
ALEIA0038GB
Revision: April 20092010 QX56

SCS-26
< COMPONENT DIAGNOSIS >
CK SUSP WARNING INDICATOR CONTROL CIRCUIT
CK SUSP WARNING INDICATOR CONTROL CIRCUIT
DescriptionINFOID:0000000005148187
The CK SUSP warning lamp is controlled by a ground signal provided to the combination meter by the sus-
pension control unit.
Component Function CheckINFOID:0000000005148188
1.CHECK WARNING LAMP OPERATION
CONSULT-III
1. Turn ignition ON.
2. Select "WARNING LAMP" of AI R LEVELIZER active test items.
3. While operating test item, check that the warning lamp activates.
Does the warning lamp operate properly?
YES >> Warning lamp is operating normally.
NO >> Refer to SCS-26, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000005148189
Regarding Wiring Diagram information, refer to SCS-29, "Wiring Diagram".
1.PERFORM SUSPENSION CONTROL SYSTEM SELF-DIAGNOSIS
CONSULT-III
1. Turn ignition ON.
2. Perform SELF DIAGNOSIS functi on of AIR LEVELIZER system.
Are any DTC's present?
YES >> Refer to SCS-34, "DTC Index".
NO >> • If warning lamp is always ON, GO TO 2. • If warning lamp is always OFF, GO TO 3
2.CHECK SUSPENSION CONTROL UNI T WARNING LAMP CONTROL
1. Turn ignition OFF.
2. Disconnect the suspension control unit connector B3.
3. Turn ignition ON.
Does the CK SUSP warning lamp turn ON?
YES >> GO TO 3.
NO >> Replace the suspension control unit. Refer to RSU-26, "
Removal and Installation".
3.CHECK CONTINUITY OF WARNING LAMP CONTROL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect suspension control unit connector B3 and combina- tion meter connector M24.
3. Check continuity between suspension control unit connector B3 (A) terminal 10 and combination meter connector M24 (B) termi-
nal 15.ON : Warning lamp turns ON
OFF : Warning lamp turns OFF
AB
Continuity
Connector Terminal Connector Terminal
B3 10 M24 15 Yes
ALLIA0693GB
Revision: April 20092010 QX56

CK SUSP WARNING INDICATOR CONTROL CIRCUITSCS-27
< COMPONENT DIAGNOSIS >
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4. Check continuity between suspension control unit connector B3 (A) terminal 10 and ground.
Are the continuity test results as specified?
YES >> Replace the combination meter. Refer to MWI-100, "Removal and Installation".
NO >> Repair harness or connector.
A —Contin u it y
Connector Terminal
B3 10Ground No
Revision: April 20092010 QX56

SCS-28
< ECU DIAGNOSIS >
SUSPENSION CONTROL UNIT
ECU DIAGNOSIS
SUSPENSION CONTROL UNIT
Reference ValueINFOID:0000000005148190
TERMINAL LAYOUT
PHYSICAL VALUES
AWLIA1640ZZ
Terminal
(Wire color) Description
ConditionReference value
(Approx.)
+ – Signal nameInput/
Output
1
(V) Ground Compressor relay output Output Ignition
switch ON Air levelizer raising vehicle
ride height
Battery voltage
3
(W) Ground Height sensor input
InputIgnition
switch
ON —0
.2 V - 4 .8 V
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 lowering 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: April 20092010 QX56

SUSPENSION CONTROL UNITSCS-35
< ECU DIAGNOSIS >
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Compressor relay [C1802] • Driving transistor for compressor 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 voltage 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
monitor voltage continues at a high level for more than 10
seconds.
• Driving transistor for exhaust valve solenoid is ON and mon- itor voltage continues at a low level for more than 5 seconds. SCS-11,
"DiagnosisProcedure".
Vehicle height adjusting malfunc-
tion (compressor)[C1804] Continuous compressor relay ON time is more than 120 sec-
onds. SCS-12,
"DiagnosisProcedure".
Vehicle height adjusting malfunc-
tion (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 Proce-
dure".
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 sup-
plying air [C1808]A suspension air compressor ON request has been in effect
for 180 seconds and the suspension air compressor has not
activated during that time. SCS-16,
"DiagnosisProcedure".
Revision: April 20092010 QX56

SCS-36
< SYMPTOM DIAGNOSIS >
SUSPENSION CONTROL SYSTEM
SYMPTOM DIAGNOSIS
SUSPENSION CONTROL SYSTEM
Symptom TableINFOID:0000000005148193
AIR LEVELIZER
SymptomPossible causeReference page
Inoperative • Suspension control unit
• Compressor motor relay
• Suspension air compressorSCS-37, "
Diagnosis Proce-
dure"
System does not raise • Suspension control unit
• Height sensor
• Compressor motor relay
• Suspension air compressor
• Leak in system
• Restriction in systemSCS-38, "Diagnosis Proce-
dure"
System does not lower
• Suspension control unit
• Height sensor
• Compressor motor relay
• Suspension air compressor
• Restriction in systemSCS-39, "Diagnosis Proce-
dure"
CK SUSP indicator lamp always ON with key ON
• CK SUSP indicator la
mp control circuit
• Suspension control unit SCS-26, "Description"
Revision: April 20092010 QX56

SUSPENSION CONTROL SYSTEM INOPERATIVESCS-37
< SYMPTOM DIAGNOSIS >
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SUSPENSION CONTROL SYSTEM INOPERATIVE
DescriptionINFOID:0000000005148194
The suspension control system does not activate. It does not raise or lower the vehicle in response to ride
height changes.
Diagnosis ProcedureINFOID:0000000005148195
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 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-23, "
Diagnosis Procedure" .
3.CHECK GENERATOR "L" CIRCUIT SIGNAL
CONSULT-III DATA MONITOR
1. Start the engine.
2. Select "ACG L" of AIR LEVELIZER 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-12, "
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 compress or 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: April 20092010 QX56

SCS-38
< SYMPTOM DIAGNOSIS >
SUSPENSION CONTROL SYSTEM DOES NOT RAISE
SUSPENSION CONTROL SYSTEM DOES NOT RAISE
DescriptionINFOID:0000000005148196
The suspension control system does not raise t he vehicle in accordance with ride height changes.
Diagnosis ProcedureINFOID:0000000005148197
1.SUSPENSION CONTROL UNIT POWER 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 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-23, "
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 compressor power and ground pass inspection?
YES >> Inspect for a weak compressor, leak or restri ction in the system. Repair or replace malfunctioning
part.
NO >> Repair or replace the malfunctioning part. HEIGT SEN
: 0.2V - 4.8V
Revision: April 20092010 QX56