Nissan Xterra. Manual - part 307

EC-354

< DTC/CIRCUIT DIAGNOSIS >

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P0507 ISC SYSTEM

P0507 ISC SYSTEM

Description

INFOID:0000000009484065

NOTE:

If DTC P0507 is displayed with other DTC, first perform the trouble diagnosis for the other DTC.

The ECM controls the engine idle speed to a specified level through the fine adjustment of the air, which is let

into the intake manifold, by operating the electric throttle control actuator. The operating of the throttle valve is

varied to allow for optimum control of the engine idling speed. The crankshaft position sensor (POS) detects

the actual engine speed and sends a signal to the ECM.

The ECM controls the electric throttle control actuator so that the engine speed coincides with the target value

memorized in the ECM. The target engine speed is the lowest speed at which the engine can operate steadily.

The optimum value stored in the ECM is determined by taking into consideration various engine conditions,

such as during warming up, deceleration and engine load (air conditioner, power steering and cooling fan

operation, etc.). 

On Board Diagnosis Logic

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DTC Confirmation Procedure

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NOTE:

• If the target idle speed is out of the specified value, perform, 

EC-125, "Idle Air Volume Learning"

,

before conducting DTC Confirmation Procedure. For the target idle speed, refer to the 

EC-497

.

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

ducting 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.

• Always perform the test at a temperature above 

−10°C(14°F).

1. Start engine and warm it up to normal operating temperature.

2. Turn ignition switch OFF and wait at least 10 seconds.

3. Turn ignition switch ON.

4. Turn ignition switch OFF and wait at least 10 seconds.

5. Start engine and run it for at least 1 minute at idle speed.

6. Check 1st trip DTC.

7. If 1st trip DTC is detected, go to 

EC-354, "Diagnosis Procedure"

.

Diagnosis Procedure

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1.

CHECK PCV HOSE CONNECTION

Confirm that PCV hose is connected correctly.
OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace.

2.

CHECK INTAKE AIR LEAK

1. Start engine and let it idle.

2. Listen for an intake air leak after the mass air flow sensor.
OK or NG

OK

>> GO TO 3.

NG

>> Discover air leak location and repair.

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0507
0507

Idle speed control sys-
tem RPM higher than 
expected

The idle speed is more than the target idle 
speed by 200 rpm or more.

• Electric throttle control actuator
• Intake air leak
• PCV system

P0507 ISC SYSTEM

EC-355

< DTC/CIRCUIT DIAGNOSIS >

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3.

REPLACE ECM

1. Stop engine.

CAUTION:

Perform Additional Service When Replacing ECM. Refer to 

EC-122, "Additional Service When

Replacing ECM"

.

2. Replace ECM.

>> INSPECTION END

EC-356

< DTC/CIRCUIT DIAGNOSIS >

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P050A, P050E COLD START CONTROL

P050A, P050E COLD START CONTROL

Description

INFOID:0000000009484069

ECM controls ignition timing and engine idle speed when engine is started with pre-warming up condition.

This control promotes the activation of three way catalyst by heating the catalyst and reduces emissions.

On Board Diagnosis Logic

INFOID:0000000009484070

NOTE:

If DTC P050A or P050E is displayed with other DTC, first perform the trouble diagnosis for other DTC.

DTC Confirmation Procedure

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DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure

before conducting the next test.

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-I

With CONSULT

1. Turn ignition switch OFF and wait at least 10 seconds.

2. Turn ignition switch ON.

3. Select “DATA MONITOR” mode with CONSULT.

4. Check the indication of “COOLAN TEMP/S”.

With GST

Follow the procedure “With CONSULT” above.
Is the value of “COOLAN TEMP/S” between 15

°C (59°F) and 36°C (97°F)?

YES

>> GO TO 3.

NO-1 [If it is below 15

°C (59°F)]>>Warm up the engine until the value of “COOLAN TEMP/S” reaches 15°C

(59

°F) or more. Retry from step 1.

NO-2 [If it is above 36

°C (97°F)]>>Cool engine down to less than 36°C (97°F). Retry from step 1.

3.

PERFORM DTC CONFIRMATION PROCEDURE-II

With CONSULT

1. Set the select lever in N range.

2. Start the engine and warm up in idle with the value of “COOLAN TEMP/S” between 15

°C (59°F) and 40°C

(104

°F) for more than 15 seconds.

3. Check 1st trip DTC.

With GST

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

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P050A

Cold start idle air control system 
performance

ECM does not control engine idle speed properly 
when engine is started with pre-warming up con-
dition.

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

P050E

Cold start engine exhaust temper-
ature too low

The temperature of the catalyst inlet does not 
rise to the proper temperature when the engine 
is started with pre-warming up condition.

P050A, P050E COLD START CONTROL

EC-357

< DTC/CIRCUIT DIAGNOSIS >

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C

D

E

F

G

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EC

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YES

>> Go to 

EC-357, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000009484072

1.

PERFORM IDLE AIR VOLUME LEARNING

Perform 

EC-125, "Idle Air Volume Learning"

.

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

• Clogging of throttle body
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, P0174. Refer to 

EC-235, "DTC Confirmation Proce-

dure"

.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Go to 

EC-236, "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-356, "DTC Confirmation Procedure"

.

Is the 1st trip DTC P050A or P050E displayed again?

YES

>> GO TO 5.

NO

>> INSPECTION END

5.

REPLACE ECM

CAUTION:

Perform Additional Service When Replacing ECM. Refer to 

EC-122, "Additional Service When Replac-

ing ECM"

.

Replace ECM.

>> INSPECTION END