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Home >> Infiniti >> 2024 >> QX80 Premium Select, AWD >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Control System (2 Of 2) >> Component /Circuit Diagnosis >> Sensor Power Supply 3 Circuit >> Diagnosis Procedure
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Diagnosis Procedure

ECM supplies a voltage of 5 V to some of the sensors systematically divided into 3 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 

NOTE: If sensor power supply 1 circuit is malfunctioning, DTC P0643 is displayed.

Sensor power supply 2 

Sensor power supply 3 

  1. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR POWER SUPPLY CIRCUIT-1 
    1. Turn ignition switch OFF.
    2. Disconnect EVAP control system pressure sensor harness connector.
    3. Turn ignition switch ON.
    4. Check the voltage between EVAP control system pressure sensor harness connector and ground.
      + - Voltage
      (Approx.)
      EVAP control system pressure sensor
      Connector Terminal
      C17 3 Ground 5 V

    Is the inspection result normal?

    YES>>

    INSPECTION END

    NO>>

    GO TO 2.

  2. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR POWER SUPPLY CIRCUIT-2 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check the continuity between EVAP control system pressure sensor harness connector and ECM harness connector.
      + - Continuity
      EVAP control system pressure sensor ECM
      Connector Terminal Connector Terminal
      C17 3 E20 125 Existed

    Is the inspection result normal?

    YES>>

    GO TO 3.

    NO>>

    Repair open circuit.

  3. CHECK SENSOR POWER SUPPLY 3 CIRCUIT 
    1. Disconnect following sensors harness connector.
    2. Check harness for short to power and short to ground, between the following terminals.
    ECM Sensor
    Connector Terminal Name Connector Terminal
    E20 125 EVAP control system pressure sensor C17 3
    F91 29 Fuel rail pressure sensor F26 1
    Engine oil pressure sensor E220 3
    Refrigerant pressure sensor E77 1
    Power steering pressure sensor F35 1

    Is the inspection result normal?

    YES>>

    GO TO 4.

    NO>>

    Repair short to ground or short to power in harness or connectors.

  4. CHECK COMPONENTS 

    Check the following.

    Is the inspection result normal?

    YES>>

    Refer to Inspection .

    NO>>

    Replace malfunctioning component.