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Home >> Infiniti >> 2004 >> QX56 RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System >> Fuel Pump Circuit >> Diagnostic Procedure
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Diagnostic 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: Checking Fuel Feed Hose
    G02691930Courtesy 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-II or tester.

      Voltage: Battery voltage 

    OK or NG

    OK: GO TO  5.

    NG: GO TO 3.

    Fig 2: Checking Fuel Pump Power Supply Circuit-I
    G02691931Courtesy of NISSAN MOTOR CO., U.S.A.
  3. CHECK FUEL PUMP POWER SUPPLY CIRCUIT-II 
    1. Turn ignition switch OFF.
    2. Disconnect IPDM E/R harness connector E122.
    3. Turn ignition switch ON.
    4. Check voltage between IPDM E/R terminal 46 and ground with CONSULT-II or tester.

      Voltage: Battery voltage 

    OK or NG

    OK: GO TO 4.

    NG: GO TO  12.

    Fig 3: Checking Fuel Pump Power Supply Circuit-II
    G02691932Courtesy of NISSAN MOTOR CO., U.S.A.
  4. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness for open or short between IPDM E/R and ECM

      : Repair harness or connectors.

  5. CHECK CONDENSER POWER SUPPLY CIRCUIT 
    1. Turn ignition switch OFF.
    2. Reconnect all harness connectors disconnected.
    3. Disconnect condenser harness connector.
    4. Turn ignition switch ON.
      Fig 4: Checking Condenser Power Supply Circuit (1 Of 2)
      G02691933Courtesy of NISSAN MOTOR CO., U.S.A.
    5. Check voltage between condenser terminal 1 and ground with CONSULT-II 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 Condenser Power Supply Circuit (2 Of 2)
    G02691934Courtesy 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 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 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  12.

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

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

    Refer to COMPONENT INSPECTION .

    OK or NG

    OK: GO TO 10.

    NG: Replace condenser.

  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. 

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

    OK or NG

    OK: GO TO  12.

    NG: GO TO 11.

    Fig 6: Checking Fuel Pump Power Supply And Ground Circuit For Open And Short
    G02691935Courtesy of NISSAN MOTOR CO., U.S.A.
  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 INTERMITTENT INCIDENT 

    Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

    OK or NG

    OK: Replace IPDM E/R.

    NG: Repair or replace harness or connectors.