Nissan Sentra Service Manual: P0643 Sensor power supply
Description
ECM supplies a voltage of 5.0 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 shorted-circuit sensor.
Sensor power supply 1
- Battery current sensor
- Crankshaft position (CKP) sensor (POS)
- Throttle position (TP) sensor
- Accelerator pedal position (APP) sensor 1
NOTE:
If sensor power supply 1 circuit is malfunctioning, DTC P0643 is displayed.
Sensor power supply 2
- Camshaft position (CMP) sensor (PHASE)
- Mass air flow (MAF) sensor
- Engine oil pressure (EOP) sensor
- Exhaust valve timing (EVT) control position sensor
- Accelerator pedal position (APP) sensor 2
- Intake manifold runner control valve position sensor
DTC Logic
DTC DETECTION LOGIC
| DTC No. | CONSULT screen terms (Trouble diagnosis content) | DTC detecting condition | Possible cause |
| 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. |
|
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.
- Turn ignition switch OFF and wait at least 10 seconds.
- Turn ignition switch ON.
- Turn ignition switch OFF and wait at least 10 seconds.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 10 V at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDUR
- Start engine and let it idle for 1 second.
- Check DTC.
Is DTC detected? YES >> Refer to EC-354, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis Procedure
1.CHECK ACCELERATOR PEDAL POSITION SENSOR 1 POWER SUPPLY CIRCUIT
- Disconnect accelerator pedal position (APP) sensor harness connector.
- Turn ignition switch ON.
- Check the voltage between APP sensor harness connector and ground.
Is the inspection result normal? YES >> GO TO 4.
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 short to ground or short to power in harness or connectors.
3.CHECK COMPONENTS
Check the following.
Is the inspection result normal? YES >> GO TO 4.
NO >> Repair or replace malfunctioning component.
4.CHECK APP SENSOR
Check APP sensor. Refer to EC-433, "Component Inspection (APP Sensor)".
Is the inspection result normal? YES >> Check intermittent incident. Refer to GI-39, "Intermittent Incident".
NO >> Replace accelerator pedal assembly. Refer to ACC-3, "Removal and Installation".
P060B ECM
DTC Logic
DTC DETECTION LOGIC
DTC No.
CONSULT screen terms
(Trouble diagnosis content)
DTC detecting condition
Possible cause
P060B
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