Nissan Altima L32. Manual - part 308

P0507 ISC SYSTEM

EC-353

< COMPONENT DIAGNOSIS >

[QR25DE FOR CALIFORNIA]

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

ment"

.

>> INSPECTION END

EC-354

< COMPONENT DIAGNOSIS >

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P0550 PSP SENSOR

P0550 PSP SENSOR

Description

INFOID:0000000004349388

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:0000000004349389

DTC DETECTION LOGIC

NOTE:

If DTC P0550 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.

>> 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-354, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000004349390

1.

CHECK GROUND CONNECTION

1. Turn ignition switch OFF.

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

GI-45, "Circuit Inspection"

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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

P0550 PSP SENSOR

EC-355

< COMPONENT DIAGNOSIS >

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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-355, "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:0000000004349391

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. 5 V

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

EC-356

< COMPONENT DIAGNOSIS >

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P0550 PSP SENSOR

4. Check the voltage between ECM harness connector and ground

under the following conditions.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace power steering pressure sensor.

ECM

Condition

Voltage

Connector

Terminal

F13

41

(Power steering pres-

sure sensor signal)

Steering 
wheel

Being turned.

0.5 - 4.5 V

Not being 
turned.

0.4 - 0.8 V

JMBIA1597ZZ