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Home >> Infiniti >> 2020 >> QX80 Luxe, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (DTCS) (4 Of 5) >> 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