Nissan Maxima. Manual - part 475

EC-384

< DTC/CIRCUIT DIAGNOSIS >

[VQ35DE]

P050A, P050E COLD START CONTROL

P050A, P050E COLD START CONTROL

Description

INFOID:0000000010095062

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.

DTC Logic

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DTC DETECTION LOGIC

NOTE:

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

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 4

°C (39°F) and 36°C (97°F)?

YES

>> GO TO 3.

NO-1 [If it is below 4

°C (39°F)]>>Warm up the engine until the value of “COOLAN TEMP/S” reaches 4°C

(39

°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?

YES

>> Go to 

EC-385, "Diagnosis Procedure"

.

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 proper-
lywhen engine is started with pre-warming up 
condition.

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

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-385

< DTC/CIRCUIT DIAGNOSIS >

[VQ35DE]

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>> INSPECTION END

Diagnosis Procedure

INFOID:0000000010095064

1.

PERFORM IDLE AIR VOLUME LEARNING

Perform 

EC-21, "IDLE AIR VOLUME LEARNING : Special Repair Requirement"

.

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-261, "DTC Logic"

.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Go to 

EC-262, "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-384, "DTC Logic"

.

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

YES

>> GO TO 5.

NO

>> INSPECTION END

5.

REPLACE ECM

1. Replace ECM.

2. Go to 

EC-17, "ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT : Special Repair Require-

ment"

.

>> INSPECTION END

EC-386

< DTC/CIRCUIT DIAGNOSIS >

[VQ35DE]

P0550 PSP SENSOR

P0550 PSP SENSOR

Description

INFOID:0000000010095065

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:0000000010095066

DTC DETECTION LOGIC

NOTE:

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

EC-394, "DTC Logic"

.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

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

ing 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.

>> 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-386, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000010095067

Regarding Wiring Diagram information, refer to 

EC-554, "Wiring Diagram"

.

1.

CHECK GROUND CONNECTION

1. Turn ignition switch OFF.

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

GI-44, "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

P0550 PSP SENSOR

EC-387

< DTC/CIRCUIT 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, 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, 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, short to ground or short to power in harness or connectors.

5.

CHECK PSP SENSOR

Refer to 

EC-387, "Component Inspection"

.

Is the inspection result normal?

YES

>> GO TO 6.

NO

>> Replace PSP sensor. Refer to 

ST-29, "Exploded View"

.

6.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-41, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000010095068

1.

CHECK POWER STEERING PRESSURE SENSOR

1. Reconnect all harness connectors disconnected.

2. 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