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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 › Fuel Injector › Diagnosis Procedure

Diagnosis Procedure

  1. CHECK FUEL INJECTOR POWER SUPPLY CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect fuel injector harness connector.
    3. Turn ignition switch ON.
    4. Check the voltage between fuel injector harness connector and ground.
      + - Voltage
      Fuel injector
      Cylinder Connector Terminal
      1 F123 1 Ground Battery voltage
      2 F124 1
      3 F125 1
      4 F126 1
      5 F127 1
      6 F128 1
      7 F129 1
      8 F130 1

    Is the inspection result normal?

    YES>>

    GO TO 9.

    NO>>

    GO TO 2.

  2. CHECK FUEL INJECTOR POWER SUPPLY CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check the continuity between fuel injector harness connector and ECM harness connector.
      Fuel injector ECM Continuity
      Cylinder Connector Terminal Connector Terminal
      1 F123 1 F91 47 Existed
      2 F124 1 5
      3 F125 1
      4 F126 1 54
      5 F127 1 7
      6 F128 1 47
      7 F129 1 54
      8 F130 1 7
    4. Also check harness for short to ground.

    Is the inspection result normal?

    YES>>

    GO TO 3.

    NO>>

    Repair or replace error-detected parts.

  3. CHECK FUEL INJECTOR DRIVER POWER SUPPLY 
    1. Reconnect ECM harness connector.
    2. Turn ignition switch ON.
    3. Check the voltage between ECM harness connector and ground.
      + - Voltage
      ECM
      Connector Terminal
      F91 1 Ground Battery voltage
      2
      6
      46

    Is the inspection result normal?

    YES>>

    Check intermittent incident. Refer to Inspection .

    NO>>

    GO TO 4.

  4. CHECK FUEL INJECTOR DRIVER POWER SUPPLY CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Disconnect fuel injector relay harness connector.
    4. Check the continuity between ECM harness connector and fuel injector relay harness connector.
      ECM Fuel injector relay Continuity
      Connector Terminal Connector Terminal
      F91 1 E26 3 Existed
      2 6
      6 3
      46 6
    5. Also check harness for short to ground.

    Is the inspection result normal?

    YES>>

    GO TO 5.

    NO>>

    Repair or replace error-detected parts

  5. CHECK FUEL INJECTOR RELAY POWER SUPPLY (CONTACT SIDE) 
    1. Turn ignition switch ON.
    2. Check the voltage between fuel injector relay harness connector and ground.
    + - Voltage
    Fuel injector relay
    Connector Terminal
    E26 5 Ground Battery voltage
    7

    Is the inspection result normal?

    YES>>

    GO TO 6.

    NO>>

    Perform the trouble diagnosis for power supply circuit.

  6. CHECK FUEL INJECTOR RELAY POWER SUPPLY (EXCITATION COIL SIDE) 
    1. Reconnect all harness connectors disconnected.
    2. Check the voltage between fuel injector relay harness connector and ground.
      + - Voltage
      Fuel injector relay
      Connector Terminal
      E26 2 Ground Battery voltage

    Is the inspection result normal?

    YES>>

    GO TO 8.

    NO>>

    GO TO 7.

  7. CHECK FUEL INJECTOR RELAY POWER SUPPLY CIRCUIT (EXCITATION COIL SIDE) 
    1. Turn ignition switch OFF.
    2. Disconnect fuel injector relay harness connector.
    3. Disconnect IPDM E/R harness connector.
    4. Check the continuity between IPDM E/R harness connector and fuel injector harness connector.
      IPDM E/R Fuel injector relay Continuity
      Connector Terminal Connector Terminal
      E14 36 E26 2 Existed
    5. Also check harness for short to ground.

    Is the inspection result normal?

    YES>>

    Perform the trouble diagnosis for power supply circuit.

    NO>>

    Repair or replace error-detected parts.

  8. CHECK FUEL INJECTOR RELAY GROUND CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect fuel injector relay harness connector.
    3. Check the continuity between fuel injector relay harness connector and ground.
      Fuel injector relay - Continuity
      Connector Terminal
      E26 1 Ground Existed
    4. Also check harness for short to power.

    Is the inspection result normal?

    YES>>

    GO TO 10.

    NO>>

    Repair or replace error-detected parts.

  9. CHECK FUEL INJECTOR GROUND CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check the continuity between fuel injector harness connector and ECM harness connector.
      Fuel injector ECM Continuity
      Cylinder Connector Terminal Connector Terminal
      1 F123 2 F91 48 Existed
      2 F124 2 9
      3 F125 2 4
      4 F126 2 49
      5 F127 2 8
      6 F128 2 52
      7 F129 2 53
      8 F130 2 3
    4. Also check harness for short to ground and to power.

    Is the inspection result normal?

    YES>>

    GO TO 11.

    NO>>

    Repair or replace error-detected parts.

  10. CHECK FUEL INJECTOR RELAY 

    Check the fuel injector relay. Refer to Component Inspection .Is the inspection result normal?

    YES>>

    Check intermittent incident. Refer to Inspection .

    NO>>

    Replace fuel injector relay.

  11. CHECK FUEL INJECTOR 

    Check the fuel injector. Refer to Component Inspection .Is the inspection result normal?

    YES>>

    Check intermittent incident. Refer to Inspection .

    NO>>

    Replace malfunctioning fuel injector. Refer to FUEL INJECTOR AND FUEL TUBE : Removal and Installation .

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