Infiniti QX56 (Z62). Manual - part 1109

C1802 AIR SUS COMPRS RELAY

SCS-73

< DTC/CIRCUIT DIAGNOSIS >

[AIR LEVELIZER CONTROL SYSTEM]

C

D

F

G

H

I

J

K

L

M

A

B

SCS

N

O

P

3.

Check continuity between air levelizer control module harness connector and air compressor relay har-
ness connector.

4.

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

5.

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

Are the inspection results normal?

YES

>> GO TO 3.

NO

>> Repair or replace damaged part. 

3.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-40, "Intermittent Incident"

.

Is the inspection result normal?

YES

>> Replace the air levelizer control module. Refer to 

SCS-94, "Removal and Installation"

.

NO

>> Repair or replace damaged parts.

4.

CHECK AIR COMPRESSOR RELAY GROUND

1.

Turn ignition switch OFF.

2.

Check continuity between air compressor relay harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 5.

NO

>> Repair or replace damaged part.

5.

CHECK AIR COMPRESSOR RELAY

1.

Remove the air compressor relay. Refer to 

SCS-50, "Component Parts Location"

.

2.

Check continuity between air compressor relay harness connector terminals.

Is the inspection result normal?

YES

>> Check intermittent incident. Refer to 

GI-40, "Intermittent Incident"

.

NO

>> Replace the air compressor relay. Refer to 

SCS-50, "Component Parts Location"

.

Air levelizer control module

Air compressor relay

Continuity

Connector

Terminal

Connector

Terminal

B84

3

E116

2

Existed

Air levelizer control module

—

Continuity

Connector

Terminal

B84

3

Ground

Not existed

Air levelizer control module

—

Voltage

Connector

Terminal

B84

3

Ground

0 V

Air compressor relay

—

Continuity

Connector

Terminal

E116

1

Ground

Existed

Air compressor relay

Continuity

Terminal

1

2

Existed

SCS-74

< DTC/CIRCUIT DIAGNOSIS >

[AIR LEVELIZER CONTROL SYSTEM]

C1803 AIR SUSPENSION EXH SOL

C1803 AIR SUSPENSION EXH SOL

DTC Logic

INFOID:0000000006256067

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 10 seconds or more.

2.

Select “EXHAUST SOLENOID” in “Active Test” in “E-SUS”.

3.

Touch “ON” and wait 5 seconds or more.

4.

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

Is “C1803” detected ?

YES

>> Go to 

SCS-74, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006256068

1.

CHECK EXHAUST SOLENOID ON SIGNAL FROM AIR LEVELIZER CONTROL MODULE

 CONSULT-III

1.

Disconnect air compressor harness connector.

2.

Turn ignition switch ON.

CAUTION:

Never start the engine.

3.

Select “EXHAUST SOLENOID” in “Active Test” in “E-SUS”.

4.

Touch “ON”.

5.

While operating test item, check voltage between air compressor harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> GO TO 2.

2.

CHECK HARNESS BETWEEN AIR LEVELIZER CONTROL MODULE AND AIR COMPRESSOR

1.

Turn ignition switch OFF.

2.

Disconnect air levelizer control module harness connector.

DTC

Display item

Malfunction detected condition

Possible cause

C1803 

AIR SUS EXH SOL

• Output voltage of the exhaust solenoid remains 9 V 

or less continuously for 5 seconds during exhaust 
solenoid ON signal output by the air levelizer con-
trol module.

• Output voltage of the exhaust solenoid remains 2 V 

or more continuously for 10 seconds during ex-
haust solenoid ON signal output by the air levelizer 
control module.

• Harness or connector
• Exhaust solenoid
• Air levelizer control module

Air compressor

—

Voltage

Connector

Terminal

C12

4

Ground

9 – 16 V

C1803 AIR SUSPENSION EXH SOL

SCS-75

< DTC/CIRCUIT DIAGNOSIS >

[AIR LEVELIZER CONTROL SYSTEM]

C

D

F

G

H

I

J

K

L

M

A

B

SCS

N

O

P

3.

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

4.

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

Are the inspection results normal?

YES

>> GO TO 3.

NO

>> Repair or replace damaged part. 

3.

CHECK INTERMITTENT INCIDENT 

Refer to 

GI-40, "Intermittent Incident"

.

Is the inspection result normal?

YES

>> Replace the air levelizer control module. Refer to 

SCS-94, "Removal and Installation"

.

NO

>> Repair or replace damaged parts.

4.

CHECK AIR COMPRESSOR GROUND

1.

Turn ignition switch OFF.

2.

Check continuity between air compressor harness connector and ground.

Are the inspection results normal?

YES

>> GO TO 5.

NO

>> Repair or replace damaged part.

5.

CHECK AIR COMPRESSOR (EXHAUST SOLENOID)

Check the air compressor (exhaust solenoid). Refer to 

SCS-75, "Component Inspection"

.

Is the inspection result normal?

YES

>> Check intermittent incident. Refer to 

GI-40, "Intermittent Incident"

.

NO

>> Replace the air compressor. Refer to 

SCS-95, "Removal and Installation"

.

Component Inspection

INFOID:0000000006256069

CAUTION:

•  Keep the inside of air compressor free of dust.
•  Keep the resin stick and resin pipe free of scratches and burrs.

1.

CHECK AIR COMPRESSOR (EXHAUST SOLENOID)

1.

Remove the air compressor. Refer to 

SCS-95, "Removal and Installation"

.

Air levelizer control module

Air compressor

Continuity

Connector

Terminal

Connector

Terminal

B84

11

C12

4

Existed

Air levelizer control module

—

Continuity

Connector

Terminal

B84

11

Ground

Not existed

Air compressor

—

Continuity

Connector

Terminal

C12

3

Ground

Existed

SCS-76

< DTC/CIRCUIT DIAGNOSIS >

[AIR LEVELIZER CONTROL SYSTEM]

C1803 AIR SUSPENSION EXH SOL

2.

Insert resin stick (A) 4.7 mm (0.185 in) in diameter into either
one of the air compressor air tube holes to prevent leakage of
air.

3.

Insert resin pipe (B) 4.7 mm (0.185 in) in diameter into the other
air tube hole and install air gauge (C) on the tip of the pipe.

4.

Apply 12 V between air compressor connector terminal 1 and 2
until the air gauge reading reaches approximately 500 mm Hg
(0.67 MPa).

CAUTION:

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

the voltage.

5.

Apply 12 V between air compressor connector terminal 3 and 4 for approximately 2 seconds.

CAUTION:

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

*: It takes approximately 2 minutes for the air gauge needle to stop moving.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace the air compressor. Refer to 

SCS-95, "Removal and Installation"

.

JSEIA0248ZZ

(+) (fuse)

(

−

)

Condition

Status

Air compressor

Terminal

1

2

Apply 12 V between air compressor connector terminal 1 and 2 
until the air gauge reading reaches approximately 500 mm Hg 
(0.67 MPa).

Air gauge needle remains at 
the pressurized position.

(+) (fuse)

(

−

)

Condition

Status

Air compressor

Terminal

4

3

Apply 12 V between air compressor connector terminal 3 and 4 
for approximately 2 seconds.

Air gauge reading lowers and 
the needle stops moving.