Nissan X-Trail 32. Manual - part 798

P0643 SENSOR POWER SUPPLY

EC-321

< DTC/CIRCUIT DIAGNOSIS >

[MR20DD]

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P0643 SENSOR POWER SUPPLY

DTC Description

INFOID:0000000010775218

ECM supplies a voltage of 5 V to some of the sensors systematically divided into 2 groups, respectively.
Accordingly, when a short circuit develops in a sensor power source, a malfunction may occur simultaneously
in the sensors belonging to the same group as the short-circuited sensor.

Sensor power supply 1

• CKP sensor (POS)
• APP sensor 1
• Exhaust valve timing control position sensor
• Electric throttle control actuator
NOTE:
If sensor power supply 1 circuit is malfunctioning, DTC P0643 is displayed.

Sensor power supply 2

• Atmospheric pressure sensor
• Refrigerant pressure sensor
• Fuel rail pressure sensor
• CMP sensor
• APP sensor 2
• Engine oil pressure sensor

DTC DETECTION LOGIC

POSSIBLE CAUSE

• Harness or connectors
- APP sensor 1 circuit is shorted.
- CKP sensor (POS) circuit is shorted.
- Intake manifold runner control valve position sensor circuit is shorted.
- TP sensor circuit is shorted.
- Refrigerant pressure sensor circuit is shorted.
• Accelerator pedal position sensor
• CKP sensor (POS)
• Intake manifold runner control valve position sensor
• Throttle position sensor
• Refrigerant pressure sensor

FAIL-SAFE

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 8 V at idle.

DTC No.

CONSULT screen terms

(Trouble diagnosis content)

DTC detecting condition

P0643

SENSOR POWER/CIRC
(Sensor reference voltage “A” circuit high)

ECM detects that the voltage of sensor power supply 1 is excessively low 
or high.

Engine operating condition in fail-safe mode

Fail safe mode

Vehicle behavior

Others

ECM stops the electric throttle control actuator control, throttle valve is maintained at a fixed 
opening (approx. 5 degrees) by the return spring.

EC-322

< DTC/CIRCUIT DIAGNOSIS >

[MR20DD]

P0643 SENSOR POWER SUPPLY

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

1.

Start engine and let it idle for 1 second.

2.

Check DTC.

Is DTC detected?

YES

>> Proceed to 

EC-322, "Diagnosis Procedure"

.

NO-1

>> To check malfunction symptom before repair: Refer to 

GI-44, "Intermittent Incident"

.

NO-2

>> Confirmation after repair: INSPECTION END

Diagnosis Procedure

INFOID:0000000010775219

1.

CHECK ACCELERATOR PEDAL POSITION SENSOR 1 POWER SUPPLY CIRCUIT

1.

Disconnect accelerator pedal position (APP) sensor harness connector.

2.

Turn ignition switch ON.

3.

Check the voltage between APP sensor harness connector and ground.

Is the inspection result normal?

YES

>> Proceed to 

EC-373, "Component Inspection"

.

NO

>> GO TO 2.

2.

CHECK SENSOR POWER SUPPLY CIRCUITS

Check harness for short to power and short to ground, between the following terminals.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair or replace malfunctioning part.

3.

CHECK COMPONENTS

Check the following.
• Exhaust valve timing control position sensor (Refer to 

EC-407, "Diagnosis Procedure"

)

• Crankshaft position sensor (Refer to 

EC-279, "Component Inspection"

)

• Throttle position sensor (Refer to 

EC-213, "Component Inspection"

)

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Repair or replace malfunctioning part.

+

−

Voltage

(Approx.)

APP sensor

Connector

Terminal

CVT models

E110

4

Ground

5  V

M/T models

E167

ECM

Sensor

Connector

Termi-

nal

Name

Connector

Terminal

F7

21

Crankshaft position sensor

CVT models

F20

1

M/T models

F126

24

Exhaust valve timing control position sensor

F104

1

F8

60

Throttle position sensor

F29

2

E16

122

APP sensor 1

CVT models

E110

4

M/T models

E167

P0850 REVERSE/NEUTRAL POSITION SWITCH

EC-323

< DTC/CIRCUIT DIAGNOSIS >

[MR20DD]

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P0850 REVERSE/NEUTRAL POSITION SWITCH

CVT

CVT : DTC Description

INFOID:0000000010775220

Transmission range switch is turn ON when the selector lever is P or N.
ECM detects the position because the continuity of the line (the ON) exists.

DTC DETECTION LOGIC

POSSIBLE CAUSE

• Harness or connectors (Park/neutral position signal circuit is open or shorted.)
• Transmission range switch

FAIL-SAFE

Not applicable

DTC CONFIRMATION PROCEDURE

1.

PERFORM COMPONENT FUNCTION CHECK

With CONSULT

NOTE:
Checks whole function of the park / neutral position signal circuit by this procedure. During this check, 1st trip
DTC may not be confirmed.
1.

Turn ignition switch ON.

2.

Select “P/N POSI SW” in “DATA MONITOR” mode of “ENGINE” using CONSULT. Then check the “P/N
POSI SW” signal as per the following conditions.

Without CONSULT

1.

Turn ignition switch ON.

2.

Check the voltage between ECM harness connector and ground as per the following conditions.

Is the inspection result normal?

YES-1 >> To check malfunction symptom before repair: Refer to 

GI-44, "Intermittent Incident"

.

YES-2 >> Confirmation after repair: INSPECTION END
NO

>> Proceed to 

EC-323, "CVT : Diagnosis Procedure"

.

CVT : Diagnosis Procedure

INFOID:0000000010775221

1.

CHECK TRANSMISSION RANGE SWITCH POWER SUPPLY

1.

Turn ignition switch OFF.

2.

Disconnect transmission range switch harness connector.

3.

Turn ignition switch ON.

DTC No.

CONSULT screen terms

(Trouble diagnosis content)

DTC detecting condition

P0850

P-N POS SW/CIRCUIT
(Park/neutral switch input circuit)

The signal of transmission range switch is not changed in the process of 
engine starting and driving.

Selector lever position

Known-good signal

P or N position

ON

Except above position

OFF

+

−

Condition

Voltage

(Approx.)

ECM

Connector

Terminal

F7

14

Ground

Selector lever

P or N

Battery voltage

Except above

0 V

EC-324

< DTC/CIRCUIT DIAGNOSIS >

[MR20DD]

P0850 REVERSE/NEUTRAL POSITION SWITCH

4.

Check the voltage between transmission range switch harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Perform the trouble diagnosis for power supply circuit.

2.

CHECK TRANSMISSION RANGE SWITCH SIGNAL CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check the continuity between transmission range switch harness connector and ECM harness connector.

4.

Also check harness for short to ground and to power.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair or replace error-detected parts.

3.

CHECK TRANSMISSION RANGE SWITCH

Check the transmission range switch. Refer to 

TM-325, "Component Inspection"

.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace transaxle assembly. Refer to 

TM-450, "Removal and Installation"

.

6M/T

6M/T : DTC Description

INFOID:0000000010775222

Reverse / neutral position switch is turn ON when the selector lever is R or N.
ECM detects the position because the continuity of the line (the ON) exists.

DTC DETECTION LOGIC

POSSIBLE CAUSE

• Harness or connectors (Reverse / neutral position signal circuit is open or shorted.)
• Reverse / neutral position switch

FAIL-SAFE

Not applicable

DTC CONFIRMATION PROCEDURE

1.

PERFORM COMPONENT FUNCTION CHECK

With CONSULT

NOTE:

+

−

Voltage

Transmission range switch

Connector

Terminal

F22

1

Ground

Battery voltage

+

−

Continuity

Transmission range switch

ECM

Connector

Terminal

Connector

Terminal

F22

2

F7

14

Existed

DTC No.

CONSULT screen terms

(Trouble diagnosis content)

DTC detecting condition

P0850

P-N POS SW/CIRCUIT
(Reverse / neutral switch input circuit)

The signal of reverse / neutral position switch is not changed in the process 
of engine starting and driving.