Nissan Altima 2007-2012 Service Manual: P0506 ISC System

Description

The ECM controls the engine idle speed to a specified level via 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.).

DTC Logic

DTC DETECTION LOGIC

NOTE: If DTC P0506 is displayed with other DTC, first perform the trouble diagnosis for the other DTC.

DTC CONFIRMATION PROCEDURE

1.PRECONDITIONING

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

If the target idle speed is out of the specified value, perform EC-1053, "IDLE AIR VOLUME LEARNING : Special Repair Requirement", before conducting DTC CONFIRMATION PROCEDURE.

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

• Always perform the test at a temperature above −10°C(14°F).

>> GO TO 2.

2.PERFORM DTC CONFIRMATION PROCEDURE

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

6. Check 1st trip DTC.

Is 1st trip DTC detected? YES >> Go to EC-1367, "Diagnosis Procedure".

NO >> INSPECTION END

Diagnosis Procedure

1.CHECK INTAKE AIR LEAKAGE

1. Start engine and let it idle.

2. Listen for an intake air leakage after the mass air flow sensor.

Is intake air leakage detected?

YES >> Discover air leakage location and repair.

NO >> GO TO 2.

2.REPLACE ECM

1. Stop engine.

2. Replace ECM.

3. Go to EC-1051, "ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT : Special Repair Requirement".

>> INSPECTION END

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