Nissan Altima L32. Instruction — part 434

P0507 ISC SYSTEM

EC-857

< COMPONENT DIAGNOSIS >

[QR25DE EXCEPT FOR CALIFORNIA]

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P0507 ISC SYSTEM

Description

INFOID:0000000004349818

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.).

DTC Logic

INFOID:0000000004349819

DTC DETECTION LOGIC

NOTE:

If DTC P0507 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 turn ignition switch OFF and wait at

least 10 seconds before conducting the next test.

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

EC-566, "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 11V 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. Start engine and run it for at least 1 minute at idle speed.

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

YES

>> Go to

EC-857, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000004349820

1.

CHECK PCV HOSE CONNECTION

Confirm that PCV hose is connected correctly.
Is the inspection result normal?

YES

>> GO TO 2.

NO

>> 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.

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0507

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

EC-858

< COMPONENT DIAGNOSIS >

[QR25DE EXCEPT FOR CALIFORNIA]

P0507 ISC SYSTEM

Is intake air leak detected?

YES

>> Discover air leak location and repair.

NO

>> GO TO 3.

3.

REPLACE ECM

1. Stop engine.

2. Replace ECM.

3. Go to

EC-563, "ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT : Special Repair Require-

ment"

.

>> INSPECTION END

P0550 PSP SENSOR

EC-859

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[QR25DE EXCEPT FOR CALIFORNIA]

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P0550 PSP SENSOR

Description

INFOID:0000000004349821

Power steering pressure (PSP) sensor is installed to the power steering high-pressure tube and detects a

power steering load.

This sensor is a potentiometer which transforms the power steering load into output voltage, and emits the

voltage signal to the ECM. The ECM controls the electric throttle control actuator and adjusts the throttle valve

opening angle to increase the engine speed and adjusts the idle speed for the increased load.

DTC Logic

INFOID:0000000004349822

DTC DETECTION LOGIC

NOTE:

If DTC P0550 is displayed with DTC P0643, first perform the trouble diagnosis for DTC P0643. Refer to

EC-867, "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.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

1. Start engine and let it idle for at least 5 seconds.

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

YES

>> Go to

EC-859, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000004349823

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 PSP SENSOR POWER SUPPLY CIRCUIT

1. Disconnect power steering pressure (PSP) sensor harness connector.

2. Turn ignition switch ON.

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0550

Power steering pressure
sensor circuit

An excessively low or high voltage from the
sensor is sent to ECM.

• Harness or connectors

(The sensor circuit is open or shorted)

• Power steering pressure sensor

EC-860

< COMPONENT DIAGNOSIS >

[QR25DE EXCEPT FOR CALIFORNIA]

P0550 PSP SENSOR

3. Check the voltage between PSP sensor harness connector and

ground.

Is the inspection result normal?

YES

>> GO TO 3.

NO

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

in harness or connectors.

3.

CHECK PSP SENSOR GROUND CIRCUIT FOR OPEN AND SHORT

1. Turn ignition switch OFF.

2. Disconnect ECM harness connector.

3. Check the continuity between PSP 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 short to ground short to power in harness or connectors.

4.

CHECK PSP SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1. Check the continuity between PSP 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 short to ground or short to power in harness or connectors.

5.

CHECK PSP SENSOR

Refer to

EC-860, "Component Inspection"

.

Is the inspection result normal?

YES

>> GO TO 6.

NO

>> Replace PSP sensor.

6.

CHECK INTERMITTENT INCIDENT

Refer to

GI-42, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000004349824

1.

CHECK POWER STEERING PRESSURE SENSOR

1. Turn ignition switch OFF.

2. Reconnect all harness connectors disconnected.

3. Start engine and let it idle.

PSP sensor

Ground

Voltage

Connector

Terminal

F40

1

Ground

Approx. 5V

JMBIA1596ZZ

PSP sensor

ECM

Continuity

Connector

Terminal

Connector

Terminal

F40

3

F13

48

Existed

PSP sensor

ECM

Continuity

Connector

Terminal

Connector

Terminal

F40

2

F13

41

Existed