Nissan Altima L32. Manual - part 314

P1421 COLD START CONTROL

EC-377

< COMPONENT DIAGNOSIS >

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P1421 COLD START CONTROL

Description

INFOID:0000000004349419

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:0000000004349420

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

If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at

least 10 seconds before conducting the next test.

TESTING CONDITION:

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

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

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.

With GST

Follow the procedure “With CONSULT-III” above.
Is 1st trip DTC detected?

YES

>> Go to 

EC-377, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000004349421

1.

PERFORM IDLE AIR VOLUME LEARNING

Perform 

EC-30, "IDLE AIR VOLUME LEARNING : Special Repair Requirement"

.

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

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

EC-378

< COMPONENT DIAGNOSIS >

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P1421 COLD START CONTROL

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair or replace malfunctioning part

3.

CHECK FUEL INJECTION SYSTEM FUNCTION

Perform DTC CONFIRMATION PROCEDURE for DTC P0171. Refer to 

EC-254, "DTC Logic"

.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Go to 

EC-255, "Diagnosis Procedure"

 for DTC P0171.

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-377, "DTC Logic"

.

 With GST

1. Turn ignition switch ON.

2. Select Service $04 with GST.

3. Perform DTC CONFIRMATION PROCEDURE.

See 

EC-377, "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-27, "ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT : Special Repair Require-

ment"

.

>> INSPECTION END

P1550 BATTERY CURRENT SENSOR

EC-379

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P1550 BATTERY CURRENT SENSOR

Description

INFOID:0000000004349422

The power generation voltage variable control enables fuel consumption to be decreased by reducing the

engine load which is caused by the power generation of the generator. The battery current 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 performing the power generation voltage variable control, ECM calculates the target power

generation voltage based on the sensor signal. And ECM sends the calculated value as the power generation

command value to IPDM E/R. For the details of the power generation voltage variable control, refer to 

CHG-5,

"System Description"

.

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.

DTC Logic

INFOID:0000000004349423

DTC DETECTION LOGIC

NOTE:

If DTC P1550 is displayed with DTC P0643, first perform the trouble diagnosis for DTC P0643. Refer to

EC-362, "DTC Logic"

.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at

least 10 seconds before conducting the next test.

TESTING CONDITION:

Before performing the following procedure, confirm that battery voltage is more than 8V at idle.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

1. Start engine and wait at least 10 seconds.

2. Check 1st trip DTC.
Is 1st trip DTC detected?

YES

>> Go to 

EC-379, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000004349424

1.

CHECK GROUND CONNECTION

1. Turn ignition switch OFF.

2. Check ground connection E9. Refer to Ground Inspection in 

GI-45, "Circuit Inspection"

. 

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Repair or replace ground connection.

2.

CHECK BATTERY CURRENT SENSOR POWER SUPPLY CIRCUIT

1. Disconnect battery current sensor harness connector.

2. Turn ignition switch ON.

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P1550

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

EC-380

< COMPONENT DIAGNOSIS >

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P1550 BATTERY CURRENT SENSOR

3. Check the voltage between battery current sensor harness con-

nector and ground.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair open circuit or sort to ground or short to power in

harness or connectors.

3.

CHECK BATTERY CURRENT SENSOR GROUND CIRCUIT FOR OPEN AND SHORT

1. Turn ignition switch OFF.

2. Disconnect ECM harness connector.

3. Check the continuity between battery current sensor harness connector and ECM harness connector.

4. Also check harness for short to ground and short to power.
Is the inspection result normal?

YES

>> GO TO 4.

NO

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

4.

CHECK BATTERY CURRENT SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1. Check the continuity between battery current sensor harness connector and ECM harness connector.

2. Also check harness for short to ground and short to power.
Is the inspection result normal?

YES

>> GO TO 5.

NO

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

5.

CHECK BATTERY CURRENT SENSOR

Refer to 

EC-380, "Component Inspection"

.

Is the inspection result normal?

YES

>> GO TO 6.

NO

>> Replace battery negative cable assembly.

6.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-42, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000004349425

1.

CHECK BATTERY CURRENT SENSOR

1. Reconnect harness connectors disconnected.

Battery current sensor

Ground

Voltage

Connector

Terminal

F5

1

Ground

Approx. 5 V

JMBIA1602ZZ

Battery current sensor

ECM

Continuity

Connector

Terminal

Connector Terminal

F5

2

F13

44

Existed

Battery current sensor

ECM

Continuity

Connector

Terminal

Connector Terminal

F5

3

F13

42

Existed