Nissan Pathfinder (2008 year). Manual - part 275

P1421 COLD START CONTROL

EC-317

< 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-179, "DTC Confirmation Procedure"

 in DTC P0171, P0174 FUEL INJECTION SYSTEM FUNC-

TION.

OK or NG

OK

>> GO TO 4.

NG

>> Go to 

EC-180, "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-316, "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-316, "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, "ECM RE-COMMUNICATING FUNCTION : Special Repair Requirement"

 (with Intelligent

Key system) or 

SEC-100, "ECM RE-COMMUNICATING FUNCTION : Special Repair Requirement"

 (with-

out Intelligent Key system).

3.

Perform 

EC-25, "VIN Registration"

.

4.

Perform 

EC-26, "Accelerator Pedal Released Position Learning"

.

5.

Perform 

EC-26, "Throttle Valve Closed Position Learning"

.

6.

Perform 

EC-26, "Idle Air Volume Learning"

.

>> INSPECTION END

EC-318

< COMPONENT DIAGNOSIS >

[VQ40DE]

P1550 BATTERY CURRENT SENSOR

P1550 BATTERY CURRENT SENSOR

Component Description

INFOID:0000000001376358

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 SC section.

CAUTION:

Do not 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:0000000001376360

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

EC-299

.

DTC Confirmation Procedure

INFOID:0000000001376361

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-318, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000001376363

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

P1550 BATTERY CURRENT SENSOR

EC-319

< COMPONENT DIAGNOSIS >

[VQ40DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

Refer to 

EC-96, "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.

EC-320

< 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-320, "Component Inspection"

.

OK or NG

OK

>> GO TO 9.

NG

>> Replace battery negative cable assembly.

9.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-47, "Work Flow"

.

>> INSPECTION END

Component Inspection

INFOID:0000000001376364

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

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

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

EC-322

< COMPONENT DIAGNOSIS >

[VQ40DE]

P1551, P1552 BATTERY CURRENT SENSOR

P1551, P1552 BATTERY CURRENT SENSOR

Component Description

INFOID:0000000001376365

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 SC section.

CAUTION:

Do not 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:0000000001376367

The MIL will not light up 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-299

.

DTC Confirmation Procedure

INFOID:0000000001376368

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-322, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000001376370

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.

P1551, P1552 BATTERY CURRENT SENSOR

EC-323

< COMPONENT DIAGNOSIS >

[VQ40DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

Refer to 

EC-96, "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.

EC-324

< COMPONENT DIAGNOSIS >

[VQ40DE]

P1551, P1552 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 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 circuit or short to ground or short to power in harness or connectors.

8.

CHECK BATTERY CURRENT SENSOR

Refer to 

EC-324, "Component Inspection"

.

OK or NG

OK

>> GO TO 9.

NG

>> Replace battery negative cable assembly.

9.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-47, "Work Flow"

.

>> INSPECTION END

Component Inspection

INFOID:0000000001376371

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