Infiniti QX56 (Z62). Manual - part 1111

C1806 VHCL HEIGHT SEN FIX

SCS-81

< DTC/CIRCUIT DIAGNOSIS >

[AIR LEVELIZER CONTROL SYSTEM]

C

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SCS

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C1806 VHCL HEIGHT SEN FIX

DTC Logic

INFOID:0000000006256076

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If “DTC CONFIRMATION PROCEDURE” has been previously conducted, always turn ignition switch OFF
andwait at least 10 seconds before conducting the next test.

>> GO TO 2.

2.

CHECK VEHICLE HEIGHT SENSOR FIXATION

 With CONSULT-III

1.

Start the engine.

2.

Select “VHCL HEIGHT SEN” in “Data Monitor” in “E-SUS”.

3.

Drive vehicle and maintain the following conditions for 5 minutes or more.

Does the value of “VHCL HEIGHT SEN” change?

YES

>> INSPECTION END

NO

>> Go to 

SCS-81, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000006256077

1.

CHECK APPEARANCE

Visually check for installation malfunction, or deformation of vehicle height sensor.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Repaire or replace damaged parts. 

2.

CHECK VEHICLE HEIGHT SENSOR

Check the vehicle height sensor. Refer to 

SCS-70, "Component Inspection"

.

Is the inspection result normal?

YES

>> Check intermittent incident. Refer to 

GI-40, "Intermittent Incident"

.

NO

>> Replace the vehicle height sensor. Refer to 

SCS-98, "Removal and Installation"

.

DTC

Display item

Malfunction detected condition

Possible cause

C1806

VHCL HEIGHT SEN FIX

The signal voltage of the vehicle height sensor does 
not change for cumulated time of 100 hours under the 
condition that the air levelizer control module outputs 
sensor voltage (4.5 – 5.5 V) with vehicle speeds 2 
km/h (2 MPH) or more.

• Harness or connector
• Vehicle height sensor

Vehicle speed

: 5 km/h (3 MPH) or more

SCS-82

< DTC/CIRCUIT DIAGNOSIS >

[AIR LEVELIZER CONTROL SYSTEM]

C1807 VHCL HEIGHT SEN VOLT

C1807 VHCL HEIGHT SEN VOLT

DTC Logic

INFOID:0000000006256078

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If “DTC CONFIRMATION PROCEDURE” has been previously conducted, always turn ignition switch OFF
andwait at least 10 seconds before conducting the next test.

>> GO TO 2.

2.

CHECK DTC DETECTION

 With CONSULT-III

1.

Turn ignition switch ON and wait 20 seconds or more.

2.

Perform “Self Diagnostic Results” in “E-SUS”.

Is “C1807” detected ?

YES

>> Go to 

SCS-82, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006256079

1.

CHECK POWER SUPPLY CIRCUIT (PART 1)

1.

Disconnect vehicle height sensor connector.

2.

Turn ignition switch ON.

CAUTION:

Never start the engine.

3.

Check voltage between the vehicle height sensor harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> GO TO 2.

2.

CHECK POWER SUPPLY CIRCUIT (PART 2)

1.

Turn ignition switch OFF.

2.

Disconnect air levelizer control module connector.

3.

Check continuity between air levelizer control module harness connector and vehicle height sensor har-
ness connector.

DTC

Display item

Malfunction detected condition

Possible cause

C1807

VHCL HEIGHT SEN VOLT

The sensor power supply is more than 5.5 V or less 
than 4.5 V continuously for 20 seconds when the ig-
nition switch is ON.

• Harness or connector
• Vehicle height sensor
• Air levelizer control module

Sensor power supply is 0.5 V or more continuously for 
1 second during 2 seconds after turning ON the igni-
tion switch.

Vehicle height sensor

—

Voltage

Connector Terminal

C13

1

Ground

4.5 – 5.5 V

Air levelizer control module

Vehicle height sensor

Continuity

Connector

Terminal

Connector

Terminal

B84

13

C13

1

Existed

C1807 VHCL HEIGHT SEN VOLT

SCS-83

< DTC/CIRCUIT DIAGNOSIS >

[AIR LEVELIZER CONTROL SYSTEM]

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4.

Check continuity between air levelizer control module harness connector and ground.

Is the inspection result normal?

YES

>> 1.

Check intermittent incident. Refer to 

GI-40, "Intermittent Incident"

.

2.

If inspection result is OK, replace the air levelizer control module. Refer to 

SCS-94, "Removal

and Installation"

.

NO

>> Repair or replace damaged parts.

3.

CHECK HARNESS BETWEEN AIR LEVELIZER CONTROL MODULE AND VEHICLE HEIGHT SENSOR

1.

Turn ignition switch OFF.

2.

Disconnect air levelizer control module connector.

3.

Check continuity between air levelizer control module harness connector and vehicle height sensor har-
ness connector.

4.

Check continuity between air levelizer control module harness connector and ground.

Are the inspection results normal?

YES

>> GO TO 4.

NO

>> Repair or replace damaged parts.

4.

CHECK VEHICLE HEIGHT SENSOR

Check the vehicle height sensor. Refer to 

SCS-70, "Component Inspection"

.

Is the inspection result normal?

YES

>> Check intermittent incident. Refer to 

GI-40, "Intermittent Incident"

.

NO

>> Replace the vehicle height sensor. Refer to 

SCS-98, "Removal and Installation"

.

Air levelizer control module

—

Continuity

Connector

Terminal

B84

13

Ground

Not existed

Air levelizer control module

Vehicle height sensor

Continuity

Connector

Terminal

Connector

Terminal

B84

5

C13

2

Existed

4

3

Air levelizer control module

—

Continuity

Connector

Terminal

B84

5

Ground

Not existed

4

SCS-84

< DTC/CIRCUIT DIAGNOSIS >

[AIR LEVELIZER CONTROL SYSTEM]

C1808 AIR SUS COMPRS FNCTN

C1808 AIR SUS COMPRS FNCTN

DTC Logic

INFOID:0000000006256080

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If “DTC CONFIRMATION PROCEDURE” has been previously conducted, always turn ignition switch OFF
andwait at least 10 seconds before conducting the next test.

>> GO TO 2.

2.

CHECK DTC DETECTION

 With CONSULT-III

1.

Set vehicle in the unloaded vehicle status.

2.

Start the engine and wait 5 minutes or more.

3.

Perform “Self Diagnostic Result” in “E-SUS”.

Is “C1808” detected ?

YES

>> Go to 

SCS-84, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006256081

1.

CHECK APPEARANCE

Visually check for malfunction of suspension components, damage of air chamber of rear shock absorber,
installation malfunction, or deformation of vehicle height sensor.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Repaire or replace damaged parts. 

2.

CHECK AIR LEAK

Apply soapy water to air tube, connecting portions between air tube and each component, and air chamber of
rear shock absorber. Check for air leakage.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repaire or replace damaged parts. 

3.

CHECK AIR COMPRESSOR RELAY POWER SUPPLY

1.

Turn ignition switch OFF.

2.

Check 30A fuse (#I).

3.

Disconnect air compressor relay connector.

4.

Check voltage between air compressor relay harness connector and ground.

DTC

Display item

Malfunction detected condition

Possible cause

C1808

AIR SUS COMPRS FNCTN

The cumulative operating time of the air compressor 
reaches 180 seconds or more.
NOTE:
Cumulative time is cleared under the following condi-
tions:
• Ignition switch: OFF
• Exhaust conditions: satisfied [Vehicle height re-

mains 15 mm (0.59 in) or more higher than the ref-
erence height for 30 seconds.]

• Harness or connector
• Vehicle height sensor
• Air compressor (exhaust sole-

noid)

• Air compressor relay
• Overloaded
• Rear shock absorber (air cham-

ber)

• Rear suspension component 

parts

• Air tube