Nissan Titan A60. Manual - part 426

EC-370

< DTC/CIRCUIT DIAGNOSIS >

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P1421 COLD START CONTROL

P1421 COLD START CONTROL

Description

INFOID:0000000006158832

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

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DTC Confirmation Procedure

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NOTE:

• If DTC Confirmation Procedure has been previously conducted, always perform the following before con-

ducting the next step. 

• If DTC P1421 is displayed with other DTC, first perform the trouble diagnosis for other DTC.
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich OFF and wait at least 10 seconds.
TESTING CONDITION:

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

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 “COOLANT 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 

EC-370, "Diagnosis Procedure"

.

Diagnosis Procedure

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1.

PERFORM IDLE AIR VOLUME LEARNING

Perform 

EC-120, "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.

NG

>> Repair or replace malfunctioning part

3.

CHECK FUEL INJECTION SYSTEM FUNCTION

Perform 

EC-226, "DTC Confirmation Procedure"

 in DTC P0171, P0174 FUEL INJECTION SYSTEM FUNC-

TION.
OK or NG

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

P1421 COLD START CONTROL

EC-371

< DTC/CIRCUIT DIAGNOSIS >

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OK

>> GO TO 4.

NG

>> Go to 

EC-227, "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-370, "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-370, "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-7, "ECM RE-COMMUNICATING FUNCTION : Special Repair Requirement"

.

3. Perform 

EC-119, "VIN Registration"

.

4. Perform 

EC-119, "Accelerator Pedal Released Position Learning"

.

5. Perform 

EC-119, "Throttle Valve Closed Position Learning"

.

6. <Flexible Fuel Vehicle>

Perform 

EC-119, "Ethanol Mixture Ratio Adaptation (Flexible Fuel Vehicle)"

.

7. Perform 

EC-120, "Idle Air Volume Learning"

.

>> INSPECTION END

EC-372

< DTC/CIRCUIT DIAGNOSIS >

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P1550 BATTERY CURRENT SENSOR

P1550 BATTERY CURRENT SENSOR

Component Description

INFOID:0000000006158836

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 (1) is installed to the battery cable at the negative termi-

nal. The sensor measures the charging/discharging current of the

battery. 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-6, "System

Description"

.

: Vehicle front

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:0000000006158837

The MIL will not light up for this self-diagnosis.

NOTE:

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

EC-345

.

DTC Confirmation Procedure

INFOID:0000000006158838

If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-

ing the next step. 
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich 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-372, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000006158839

1.

CHECK GROUND CONNECTIONS

1. Turn ignition switch OFF.

2. Loosen and retighten ground screws on the body. 

BBIA0744E

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-373

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EC

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Refer to 

EC-139, "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 (1) harness connector.

2. Turn ignition switch ON.

: Vehicle front

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.

Refer to Wiring Diagram.

4. Also check harness for short to ground and short to power.
OK or NG

OK

>> GO TO 6.

NG

>> GO TO 5.

BBIA0354E

BBIA0744E

Voltage: Approximately 5V

PBIA9891J

Continuity should exist.