Infiniti QX56 (Z62). Manual — part 1110

C1804 VHCL HEIGHT ADJ UP

SCS-77

< DTC/CIRCUIT DIAGNOSIS >

[AIR LEVELIZER CONTROL SYSTEM]

C

D

F

G

H

I

J

K

L

M

A

B

SCS

N

O

P

C1804 VHCL HEIGHT ADJ UP

DTC Logic

INFOID:0000000006256070

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 150 seconds or more.

3.

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

Is “C1804” detected ?

YES

>> Go to

SCS-77, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006256071

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

C1804

VHCL HEIGHT ADJ UP

The vehicle height is 15 mm (0.59 in) or more lower
than the reference height despite the output of air
compressor ON signal continuously for 120 seconds
by the air levelizer control module.

• Harness or connector
• Air compressor
• Air compressor relay
• Air levelizer control module
• Rear shock absorber (air cham-

ber)

• Vehicle height sensor
• Air tube
• Rear suspension component

parts

• Overloaded

SCS-78

< DTC/CIRCUIT DIAGNOSIS >

[AIR LEVELIZER CONTROL SYSTEM]

C1804 VHCL HEIGHT ADJ UP

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Repair or replace damaged part.

4.

CHECK AIR COMPRESSOR RELAY OUTPUT CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect air compressor connector.

3.

Check continuity between air compressor relay harness connector and air compressor harness connector.

4.

Check continuity between air compressor relay harness connector and ground.

Are the inspection results normal?

YES

>> GO TO 5.

NO

>> Repair or replace damaged part.

5.

CHECK AIR COMPRESSOR GROUND

Check continuity between air compressor harness connector and ground.

Are the inspection results normal?

YES

>> GO TO 6.

NO

>> Repair or replace damaged part.

6.

CHECK AIR COMPRESSOR RELAY

Check the air compressor relay. Refer to

SCS-79, "Component Inspection (Air Compressor Relay)"

.

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> Replace the air compressor relay.

7.

CHECK AIR COMPRESSOR

Check the air compressor. Refer to

SCS-79, "Component Inspection (Air Compressor)"

.

Is the inspection result normal?

YES

>> GO TO 8.

NO

>> Replace the air compressor. Refer to

SCS-95, "Removal and Installation"

.

8.

CHECK INTERMITTENT INCIDENT

Refer to

GI-40, "Intermittent Incident"

.

Is the inspection result normal?

YES

>> 1.

Perform “STANDARD VEHICLE HEIGHT SETTING”. Refer to

SCS-67, "Work Procedure"

.

2.

If DTC is detected, replace the air levelizer control module. Refer to

SCS-94, "Removal and

Installation"

.

Air compressor relay

—

Voltage

Connector

Terminal

E116

5

Ground

Battery voltage

Air compressor relay

Air compressor

Continuity

Connector

Terminal

Connector

Terminal

E116

3

C12

1

Existed

Air compressor relay

—

Continuity

Connector

Terminal

E116

3

Ground

Not existed

Air compressor

—

Continuity

Connector

Terminal

C12

2

Ground

Existed

C1804 VHCL HEIGHT ADJ UP

SCS-79

< DTC/CIRCUIT DIAGNOSIS >

[AIR LEVELIZER CONTROL SYSTEM]

C

D

F

G

H

I

J

K

L

M

A

B

SCS

N

O

P

NO

>> Repair or replace damaged part.

Component Inspection (Air Compressor Relay)

INFOID:0000000006256072

1.

CHECK AIR COMPRESSOR RELAY

1.

Remove the air compressor relay. Refer to

SCS-50, "Component Parts Location"

.

2.

Apply 12 V direct current between air compressor relay terminals 1 and 2.

CAUTION:

• Never make the terminals short.
• Connect the fuse between the terminals when applying the voltage.

3.

Check continuity between air compressor relay terminals 3 and 5.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace the air compressor relay. Refer to

SCS-50, "Component Parts Location"

.

Component Inspection (Air Compressor)

INFOID:0000000006256073

CAUTION:

Keep the inside of air compressor free of dust.

1.

CHECK AIR COMPRESSOR

1.

Remove the air compressor. Refer to

SCS-95, "Removal and Installation"

.

2.

Apply 12 V direct current between air compressor terminals 1 and 2.

CAUTION:

• Never make the terminals short.
• Connect the fuse between the terminals when applying the voltage.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace the air compressor. Refer to

SCS-95, "Removal and Installation"

.

(+) (fuse)

(

−

)

Condition

Continuity

Air compressor relay

Terminal

2

1

Apply 12 V direct current between terminals 2 and 1.

Existed

—

—

Does not apply 12 V direct current between terminals 2 and 1.

Not existed

(+) (fuse)

(

−

)

Condition

Status

Air compressor

Terminal

1

2

Apply 12 V direct current between terminals 1 and 2.

Air flows from air exhaust holes.

SCS-80

< DTC/CIRCUIT DIAGNOSIS >

[AIR LEVELIZER CONTROL SYSTEM]

C1805 VHCL HEIGHT ADJ DOWN

C1805 VHCL HEIGHT ADJ DOWN

DTC Logic

INFOID:0000000006256074

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.

Start the engine and wait 150 seconds or more.

2.

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

Is “C1805” detected ?

YES

>> Go to

SCS-80, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006256075

1.

CHECK APPEARANCE

Visually check for malfunction of suspension components, crush of air tube, installation malfunction, or defor-
mation of vehicle height sensor.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Repaire or replace damaged parts.

2.

CHECK INTERMITTENT INCIDENT

Refer to

GI-40, "Intermittent Incident"

.

Is the inspection result normal?

YES

>> Perform “STANDARD VEHICLE HEIGHT SETTING”. Refer to

SCS-67, "Work Procedure"

.

NO

>> Repair or replace damaged part.

DTC

Display item

Malfunction detected condition

Possible cause

C1805

VHCL HEIGHT ADJ DOWN

The vehicle height is 15 mm (0.59 in) or more raise than
the reference height despite the output of exhaust sole-
noid ON signal continuously for 120 seconds by the air
levelizer control module.

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

noid)

• Air tube
• Rear suspension component

parts