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Home >> Infiniti >> 2024 >> QX80 Premium Select, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (DTCS) (3 Of 4) >> Engine (ECM) >> DTC P1220: Fuel Pump Control Module (FPCM) >> DTC Diagnosis Procedure
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DTC Diagnosis Procedure

  1. CHECK FUEL PUMP RELAY POWER SUPPLY 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Turn ignition switch ON.
    4. Check the voltage between ECM harness connector terminals.
      ECM Voltage
      Connector + Connector -
      Terminal Terminal
      F92 93 E20 152 Battery voltage

    Is the inspection result normal?

    YES>>

    GO TO 3.

    NO>>

    GO TO 2.

  2. CHECK FUEL PUMP RELAY POWER SUPPLY CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect IPDM E/R harness connector.
    3. Check the continuity between ECM harness connector and IPDM E/R harness connector.
      + - Continuity
      ECM IPDM E/R
      Connector Terminal Connector Terminal
      F92 93 E13 31 Existed
    4. 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.

  3. CHECK FPCM POWER SUPPLY 
    1. Turn ignition switch OFF.
    2. Reconnect ECM harness connector.
    3. Disconnect FPCM harness connector.
    4. Turn ignition switch ON.
    5. Check the voltage between FPCM harness connector and ground.
      FPCM Ground Voltage
      Connector Terminal
      B1 6 Ground Battery voltage

    Is the inspection result normal?

    YES>>

    GO TO 5.

    NO>>

    GO TO 4.

  4. CHECK FPCM POWER SUPPLY CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect IPDM E/R harness connector.
    3. Check the continuity between FPCM harness connector and IPDM E/R harness connector.
      + - Continuity
      FPCM IPDM E/R
      Connector Terminal Connector Terminal
      B1 6 E15 54 Existed
    4. 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.

  5. CHECK FPCM GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Check the continuity between FPCM harness connector and ground.
      FPCM Ground Continuity
      Connector Terminal
      B1 3 Ground Existed
    3. Also check harness for short to power.

    Is the inspection result normal?

    YES>>

    GO TO 6.

    NO>>

    Repair open circuit or short to power in harness or connectors.

  6. CHECK FPCM INPUT AND OUTPUT CIRCUITS FOR OPEN AND SHORT 
    1. Disconnect ECM harness connector.
    2. Check the continuity between FPCM harness connector and ECM harness connector.
      FPCM ECM Continuity
      Connector Terminal Connector Terminal
      B1 4 E20 130 Existed
      5 136
    3. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    YES>>

    GO TO 8.

    NO>>

    GO TO 7.

  7. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness for open or short between FPCM and ECM
    • Loose or poor connection for each connector and harness

    >>

    Repair open circuit, short to ground or short to power in harness or connectors.

  8. CHECK FUEL PUMP CONTROL CIRCUIT FOR OPEN AND SHORT 
    1. Disconnect fuel level sensor unit and fuel pump harness connector.
    2. Check the continuity between FPCM harness connector and fuel level sensor unit and fuel pump harness connector.
      FPCM Fuel level sensor unit and fuel pump Continuity
      Connector Terminal Connector Terminal
      B1 1 C5 1 Existed
      2 3
    3. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    YES>>

    GO TO 9.

    NO>>

    Repair open circuit, short to ground or short to power in harness or connectors.

  9. CHECK FPCM 

    Refer to Component Inspection . Is the inspection result normal?

    YES>>

    GO TO 10.

    NO>>

    Replace FPCM.

  10. CHECK INTERMITTENT INCIDENT 

    Refer to Inspection .

    >>

    INSPECTION END

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