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Home >> Infiniti >> 2009 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Component Testing >> Fuel Pump >> Diagnosis Procedure
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Diagnosis Procedure

  1. CHECK OVERALL FUNCTION
    1. Turn ignition switch ON.
    2. Pinch fuel feed hose with two fingers.

      Fuel pressure pulsation should be felt on the fuel feed hose for 1 second after ignition switch is turned ON. 

      OK or NG 

      OK: INSPECTION END 

      NG: GO TO 2.

      Fig 1: Pinching Fuel Feed Hose
      G06315846Courtesy of NISSAN MOTOR CO., U.S.A.
  2. CHECK FUEL PUMP POWER SUPPLY CIRCUIT-I
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Turn ignition switch ON.
    4. Check voltage between ECM terminal 113 and ground with CONSULT-III or tester.

      Voltage: Battery voltage 

      OK or NG 

      OK: GO TO  5.

      NG: GO TO 3.

      Fig 2: Check Voltage Between ECM Terminal 113 And Ground
      G06315847Courtesy of NISSAN MOTOR CO., U.S.A.
  3. CHECK FUEL PUMP POWER SUPPLY CIRCUIT-II

    Check voltage between IPDM E/R terminal 46 and ground with CONSULT-III or tester.

    Voltage: Battery voltage 

    OK or NG 

    OK: GO TO 4.

    NG: GO TO  13.

    Fig 3: Checking Voltage Between IPDM E/R Terminal 46 And Ground
    G06315848Courtesy of NISSAN MOTOR CO., U.S.A.
  4. DETECT MALFUNCTIONING PART

    Check harness for open or short between IPDM E/R and ECM.

    Repair harness or connectors.

  5. CHECK CONDENSER-2 POWER SUPPLY CIRCUIT
    1. Turn ignition switch OFF.
    2. Reconnect all harness connectors disconnected.
    3. Disconnect condenser-2 harness connector.
    4. Turn ignition switch ON.
      Fig 4: Identifying Condenser-2 Harness Connector And IPDM E/R
      G06315849Courtesy of NISSAN MOTOR CO., U.S.A.
    5. Check voltage between condenser-2 terminal 1 and ground with CONSULT-III or tester.

      Voltage: Battery voltage should exist for 1 second after ignition switch is turned ON. 

    6. Also check harness for short to ground and short to power.

      OK or NG 

      OK: GO TO  8.

      NG: GO TO 6.

      Fig 5: Checking Voltage Between Condenser-2 Terminal 1 And Ground
      G06315850Courtesy of NISSAN MOTOR CO., U.S.A.
  6. CHECK 15A FUSE
    1. Turn ignition switch OFF.
    2. Disconnect 15A fuse.
    3. Check 15A fuse.

      OK or NG 

      OK: GO TO 7.

      NG: Replace fuse.

  7. CHECK CONDENSER-2 POWER SUPPLY CIRCUIT-II FOR OPEN AND SHORT
    1. Disconnect IPDM E/R harness connector E119.
    2. Check harness continuity between IPDM E/R terminal 13 and condenser-2 terminal 1.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    3. Also check harness for short to ground and short to power.

      OK or NG 

      OK: GO TO  13.

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

  8. CHECK CONDENSER-2 GROUND CIRCUIT FOR OPEN AND SHORT
    1. Check harness continuity between condenser-2

      + terminal 2 and ground.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    2. Also check harness for short to power.

      OK or NG 

      OK: GO TO 9.

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

  9. CHECK CONDENSER-2

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO 10.

    NG: Replace condenser-2.

  10. CHECK FUEL PUMP POWER SUPPLY AND GROUND CIRCUIT FOR OPEN AND SHORT
    1. Turn ignition switch OFF.
    2. Disconnect "fuel level sensor unit and fuel pump" harness connector.
    3. Disconnect IPDM E/R harness connector E119.
    4. Check harness continuity between IPDM E/R terminal 13 and "fuel level sensor unit and fuel pump" terminal 1, "fuel level sensor unit and fuel pump" terminal 3 and ground.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

      Fig 6: Identifying Fuel Level Sensor Unit And Fuel Pump Harness Connector
      G06315851Courtesy of NISSAN MOTOR CO., U.S.A.
    5. Also check harness for short to ground and short to power.

      OK or NG 

      OK: GO TO  12.

      NG: GO TO 11.

  11. DETECT MALFUNCTIONING PART

    Check the following.

    • Harness connectors E41, C1
    • Harness for open or short between fuel pump and IPDM E/R
    • Harness for open or short between fuel pump and ground

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

  12. CHECK FUEL PUMP

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO 13.

    NG: Replace "fuel level sensor unit and fuel pump".

  13. CHECK INTERMITTENT INCIDENT

    Refer to "HOW TO CHECK TERMINAL "and "INTERMITTENT INCIDENT ".

    OK or NG 

    OK: Replace IPDM E/R.

    NG: Repair or replace harness or connectors.

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