Infiniti QX56 (Z62). Manual - part 607

EC-406

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P1225 TP SENSOR

P1225 TP SENSOR

DTC Logic

INFOID:0000000006217915

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Turn ignition switch OFF and wait at least 10 seconds.

TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is 10 V or more at idle.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

1.

Turn ignition switch ON.

2.

Turn ignition switch OFF and wait at least 10 seconds.

3.

Turn ignition switch ON.

4.

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Go to 

EC-406, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006217916

1.

CHECK ELECTRIC THROTTLE CONTROL ACTUATOR VISUALLY

1.

Turn ignition switch OFF.

2.

Remove the intake air duct.

3.

Check if foreign matter is caught between the throttle valve and the housing.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Remove the foreign matter and clean the electric throttle control actuator inside, then perform

throttle valve closed position learning. Refer to 

EC-147, "Work Procedure"

.

2.

REPLACE ELECTRIC THROTTLE CONTROL ACTUATOR

Replace electric throttle control actuator. Refer to 

EM-30, "Removal and Installation"

.

>> INSPECTION END

DTC No.

Trouble diagnosis name

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P1225

CTP LEARNING-B1
(Closed throttle position 
learning performance)

Closed throttle position learning value is 
excessively low.

• Electric throttle control actuator

(TP sensor 1 and 2)

P1226 TP SENSOR

EC-407

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

P1226 TP SENSOR

DTC Logic

INFOID:0000000006217917

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Turn ignition switch OFF and wait at least 10 seconds.

TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is 10 V or more at idle.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

1.

Turn ignition switch ON.

2.

Turn ignition switch OFF and wait at least 10 seconds.

3.

Turn ignition switch ON.

4.

Repeat steps 2 and 3 for 32 times.

5.

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Go to 

EC-407, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006217918

1.

CHECK ELECTRIC THROTTLE CONTROL ACTUATOR VISUALLY

1.

Turn ignition switch OFF.

2.

Remove the intake air duct.

3.

Check if foreign matter is caught between the throttle valve and the housing.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Remove the foreign matter and clean the electric throttle control actuator inside, then perform

throttle valve closed position learning. Refer to 

EC-147, "Work Procedure"

.

2.

REPLACE ELECTRIC THROTTLE CONTROL ACTUATOR

Replace electric throttle control actuator. Refer to 

EM-30, "Removal and Installation"

.

>> INSPECTION END

DTC No.

Trouble diagnosis name

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P1226

CTP LEARNING-B1
(Closed throttle position 
learning performance)

Closed throttle position learning is not per-
formed successfully, repeatedly.

• Electric throttle control actuator

(TP sensor 1 and 2)

EC-408

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P1421 COLD START CONTROL

P1421 COLD START CONTROL

Description

INFOID:0000000006288263

ECM controls ignition timing and engine idle speed when engine is started with prewarming up condition.
This control promotes the activation of three way catalyst by heating the catalyst and reduces emissions.

DTC Logic

INFOID:0000000006288264

DTC DETECTION LOGIC

NOTE:
• If DTC P1421 is displayed with other DTC, first perform the trouble diagnosis for other DTC.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Turn ignition switch OFF and wait at least 10 seconds.

TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 11 V at idle.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Select “DATA MONITOR” mode with CONSULT-III.

4.

Check the indication of “COOLAN TEMP/S”.
If it is between 7

°

C (45

°

F) and 36

°

C (97

°

F), go to the following steps.

If it is below 7

°

C (45

°

F), warm engine up to more than 7

°

C (45

°

F) and retry from step 1.

If it is above 36

°

C (97

°

F), cool engine down to less than 36

°

C (97

°

F) and retry from step 1.

5.

Start engine and let it idle for 5 minutes.

6.

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Go to 

EC-408, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006288265

1.

PERFORM IDLE AIR VOLUME LEARNING

Perform 

EC-148, "Work Procedure"

.

Is Idle Air Volume Learning carried out successfully?

YES

>> GO TO 2.

NO

>> Follow the instruction of Idle Air Volume Learning.

2.

CHECK INTAKE SYSTEM

Check for the cause of intake air volume lacking. Refer to the following.
• Crushed intake air passage
• Intake air passage clogging
Is the inspection result normal?

YES

>> GO TO 3.

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P1421

Cold start emission reduction 
strategy monitoring

ECM does not control ignition timing and engine 
idle speed properly when engine is started with 
prewarming up condition.

• Lack of intake air volume
• Fuel injection system
• ECM

P1421 COLD START CONTROL

EC-409

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

NO

>> Repair or replace malfunctioning part

3.

CHECK FUEL INJECTION SYSTEM FUNCTION

Perform DTC Confirmation Procedure for DTC P0171, P0174. Refer to 

EC-263, "DTC Logic"

.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Go to 

EC-264, "Diagnosis Procedure"

 for DTC P0171, P0174.

4.

PERFORM DTC CONFIRMATION PROCEDURE

1.

Turn ignition switch ON.

2.

Erase DTC.

3.

Perform DTC Confirmation Procedure.
See 

EC-408, "DTC Logic"

.

Is the 1st trip DTC P1421 displayed again?

YES

>> GO TO 5.

NO

>> INSPECTION END

5.

REPLACE ECM

1.

Replace ECM.

2.

Go to 

EC-143, "Work Procedure"

.

>> INSPECTION END