Nissan Pathfinder (2009 year). Manual - part 288

EC-318

< COMPONENT DIAGNOSIS >

[VQ40DE]

P1421 COLD START CONTROL

P1421 COLD START CONTROL

Description

INFOID:0000000004297535

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.

On Board Diagnosis Logic

INFOID:0000000004297536

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

DTC Confirmation Procedure

INFOID:0000000004297537

NOTE:
If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next step.
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 11V at idle.

 WITH CONSULT-III

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 that the “COOLAN TEMP/S” indication is between 4

°

C (39

°

F) and 36

°

C (97

°

F).

If “COOLAN TEMP/S” indication is within the specified value, go to the following step.
If “COOLAN TEMP/S” indication is out of the specified value, cool engine down or warm engine up and go
to step 1.

5.

Start engine and let it idle for 5 minutes.

6.

Check 1st trip DTC.

7.

If 1st trip DTC is detected, go to "DTC Confirmation Procedure".

 WITH GST

Follow the procedure “WITH CONSULT-III” above.

Diagnosis Procedure

INFOID:0000000004297538

1.

PERFORM IDLE AIR VOLUME LEARNING

Perform 

EC-25, "Idle Air Volume Learning"

.

Is Idle Air Volume Learning carried out successfully?

Yes or No

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
OK or NG

OK

>> GO TO 3.

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P1421
1421

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

2009 Pathfinder

P1421 COLD START CONTROL

EC-319

< COMPONENT DIAGNOSIS >

[VQ40DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

NG

>> Repair or replace malfunctioning part

3.

CHECK FUEL INJECTION SYSTEM FUNCTION

Perform 

EC-181, "DTC Confirmation Procedure"

 in DTC P0171, P0174 FUEL INJECTION SYSTEM FUNC-

TION.

OK or NG

OK

>> GO TO 4.

NG

>> Go to 

EC-182, "Diagnosis Procedure"

.

4.

PERFORM DTC CONFIRMATION PROCEDURE

 With CONSULT-III

1.

Turn ignition switch ON.

2.

Select “SELF DIAG RESULTS” mode with CONSULT-III.

3.

Touch “ERASE”.

4.

Perform DTC Confirmation Procedure.
See 

EC-318, "DTC Confirmation Procedure"

.

5.

Is the 1st trip DTC P1421 displayed again?

 With GST

1.

Turn ignition switch ON.

2.

Select Service $04 with GST.

3.

Perform DTC Confirmation Procedure.
See 

EC-318, "DTC Confirmation Procedure"

.

4.

Is the 1st trip DTC P1421 displayed again?

Yes or No

Yes

>> GO TO 5.

No

>> INSPECTION END

5.

REPLACE ECM

1.

Replace ECM.

2.

Perform initialization of NVIS (NATS) system and registration of all NVIS (NATS) ignition key IDs.
Refer to 

SEC-8, "ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT : Special Repair

Requirement"

 (with Intelligent Key system) or 

SEC-124, "ADDITIONAL SERVICE WHEN REPLACING

CONTROL UNIT : Special Repair Requirement"

 (without Intelligent Key system).

3.

Perform 

EC-25, "VIN Registration"

.

4.

Perform 

EC-25, "Accelerator Pedal Released Position Learning"

.

5.

Perform 

EC-25, "Throttle Valve Closed Position Learning"

.

6.

Perform 

EC-25, "Idle Air Volume Learning"

.

>> INSPECTION END

2009 Pathfinder

EC-320

< COMPONENT DIAGNOSIS >

[VQ40DE]

P1550 BATTERY CURRENT SENSOR

P1550 BATTERY CURRENT SENSOR

Component Description

INFOID:0000000004297539

The power generation voltage variable control enables fuel con-
sumption to be decreased by reducing the engine load which is
caused by the power generation of the generator. The battery cur-
rent sensor is installed to the battery cable at the negative terminal.
The sensor measures the charging/discharging current of the bat-
tery. Based on the sensor signal, ECM judges whether or not the
power generation voltage variable control is performed. When per-
forming the power generation voltage variable control, ECM calcu-
lates the target power generation voltage based on the sensor
signal. And ECM sends the calculated value as the power genera-
tion command value to IPDM E/R. For the details of the power gen-
eration voltage variable control, refer to 

CHG-7, "System

Description"

.

CAUTION:

Never connect the electrical component or the ground wire directly to the battery terminal.The con-
nection causes the malfunction of the power generation voltage variable control, and then battery dis-
charge may occur.

On Board Diagnosis Logic

INFOID:0000000004297540

The MIL will not illuminate for this diagnosis.
NOTE:
If DTC P1550 is displayed with DTC P0643, first perform the trouble diagnosis for DTC P0643. Refer to

EC-302

.

DTC Confirmation Procedure

INFOID:0000000004297541

NOTE:
If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next step.
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 8V at idle.
1.

Start engine and wait at least 10 seconds.

2.

Check 1st trip DTC.

3.

If 1st trip DTC is detected, go to 

EC-320, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000004297542

1.

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

Loosen and retighten three ground screws on the body.

BBIA0582E

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P1550
1550

Battery current sensor circuit 
range/performance

The output voltage of the battery current 
sensor remains within the specified 
range while engine is running.

• Harness or connectors

(The sensor circuit is open or shorted.)

• Battery current sensor

2009 Pathfinder

P1550 BATTERY CURRENT SENSOR

EC-321

< COMPONENT DIAGNOSIS >

[VQ40DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

Refer to 

EC-95, "Ground Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2.

CHECK BATTERY CURRENT SENSOR POWER SUPPLY CIRCUIT

1.

Disconnect battery current sensor harness connector.

2.

Turn ignition switch ON.

3.

Check voltage between battery current sensor terminal 1 and
ground with CONSULT-III or tester.

OK or NG

OK

>> GO TO 4.

NG

>> GO TO 3.

3.

DETECT MALFUNCTIONING PART

Check the following.
• Harness connectors E5, F14
• Harness for open or short between battery current sensor and ECM

>> Repair open circuit or short to ground or short to power in harness or connectors.

4.

CHECK BATTERY CURRENT SENSOR GROUND CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check harness continuity between battery current sensor terminal 2 and ECM terminal 67.

4.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 6.

NG

>> GO TO 5.

BBIA0539E

BBIA0582E

Voltage: Approximately 5V

PBIB2609E

Continuity should exist.

2009 Pathfinder

EC-322

< COMPONENT DIAGNOSIS >

[VQ40DE]

P1550 BATTERY CURRENT SENSOR

5.

DETECT MALFUNCTIONING PART

Check the following.
• Harness connectors E5, F14
• Harness for open or short between battery current sensor and ECM

>> Repair open circuit or short to ground or short to power in harness or connectors.

6.

CHECK BATTERY CURRENT SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Check harness continuity between battery current sensor terminal 3 and ECM terminal 71.

2.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 8.

NG

>> GO TO 7.

7.

DETECT MALFUNCTIONING PART

Check the following.
• Harness connectors E5, F14
• Harness for open or short between battery current sensor and ECM

>> Repair open circuit or short to ground or short to power in harness or connectors.

8.

CHECK BATTERY CURRENT SENSOR

Refer to 

EC-322, "Component Inspection"

.

OK or NG

OK

>> GO TO 9.

NG

>> Replace battery negative cable assembly.

9.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-49, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000004297543

BATTERY CURRENT SENSOR

1.

Reconnect harness connectors disconnected.

2.

Disconnect battery negative cable.

3.

Install jumper cable between battery negative terminal and body
ground.

4.

Turn ignition switch ON.

Continuity should exist.

BBIA0588E

2009 Pathfinder

P1550 BATTERY CURRENT SENSOR

EC-323

< COMPONENT DIAGNOSIS >

[VQ40DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

5.

Check voltage between ECM terminal 71 (battery current sensor
signal) and ground.

6.

If NG, replace battery negative cable assembly.

Voltage: Approximately 2.5V

PBIB2617E

2009 Pathfinder

EC-324

< COMPONENT DIAGNOSIS >

[VQ40DE]

P1551, P1552 BATTERY CURRENT SENSOR

P1551, P1552 BATTERY CURRENT SENSOR

Component Description

INFOID:0000000004297544

The power generation voltage variable control enables fuel con-
sumption to be decreased by reducing the engine load which is
caused by the power generation of the generator. The battery cur-
rent sensor is installed to the battery cable at the negative terminal.
The sensor measures the charging/discharging current of the bat-
tery. Based on the sensor signal, ECM judges whether or not the
power generation voltage variable control is performed. When per-
forming the power generation voltage variable control, ECM calcu-
lates the target power generation voltage based on the sensor
signal. And ECM sends the calculated value as the power genera-
tion command value to IPDM E/R. For the details of the power gen-
eration voltage variable control, refer to 

CHG-7, "System

Description"

.

CAUTION:

Never connect the electrical component or the ground wire directly to the battery terminal. The con-
nection causes the malfunction of the power generation voltage variable control, and then the battery
discharge may occur.

On Board Diagnosis Logic

INFOID:0000000004297545

The MIL will not illuminate for this diagnosis.
NOTE:
If DTC P1551 or P1552 is displayed with DTC P0643, first perform the trouble diagnosis for DTC P0643.
Refer to 

EC-302

.

DTC Confirmation Procedure

INFOID:0000000004297546

NOTE:
If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next step.
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 8V with ignition
switch ON

1.

Turn ignition switch ON and wait at least 10 seconds.

2.

Check 1st trip DTC.

3.

If 1st trip DTC is detected, go to 

EC-324, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000004297547

1.

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

Loosen and retighten three ground screws on the body.

BBIA0582E

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P1551
1551

Battery current sensor circuit 
low input

An excessively low voltage from the sen-
sor is sent to ECM.

• Harness or connectors

(The sensor circuit is open or shorted.)

• Battery current sensor

P1552
1552

Battery current sensor circuit 
high input

An excessively high voltage from the sen-
sor is sent to ECM.

2009 Pathfinder

P1551, P1552 BATTERY CURRENT SENSOR

EC-325

< COMPONENT DIAGNOSIS >

[VQ40DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

Refer to 

EC-95, "Ground Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2.

CHECK BATTERY CURRENT SENSOR POWER SUPPLY CIRCUIT

1.

Disconnect battery current sensor harness connector.

2.

Turn ignition switch ON.

3.

Check voltage between battery current sensor terminal 1 and
ground with CONSULT-III or tester.

OK or NG

OK

>> GO TO 4.

NG

>> GO TO 3.

3.

DETECT MALFUNCTIONING PART

Check the following.
• Harness connectors E5, F14
• Harness for open or short between battery current sensor and ECM

>> Repair circuit or short to ground or short to power in harness or connectors.

4.

CHECK BATTERY CURRENT SENSOR GROUND CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check harness continuity between battery current sensor terminal 2 and ECM terminal 67.

4.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 6.

NG

>> GO TO 5.

BBIA0539E

BBIA0582E

Voltage: Approximately 5V

PBIB2609E

Continuity should exist.

2009 Pathfinder