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Home >> Infiniti >> 2005 >> Q45 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - System Testing >> 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 5 second after ignition switch is turned ON. 

    OK or NG 

    1. OK: INSPECTION END 
    2. NG: GO TO 2.
    Fig 1: Identifying Fuel Feed Hose Pinch Area
    G02369849Courtesy of NISSAN MOTOR CO., U.S.A.
  2. CHECK FUEL PUMP RELAY POWER SUPPLY CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect fuel pump relay
    3. Turn ignition switch ON.
      Fig 2: Locating Fuel Pump Relay
      G02369850Courtesy of NISSAN MOTOR CO., U.S.A.
    4. Check voltage between fuel pump relay terminals 2, 3 and ground with CONSULT-II or tester.
      1. Voltage: Battery voltage 

    OK or NG 

    1. OK: GO TO  4.
    2. NG: GO TO 3.
    Fig 3: Checking Voltage Between Fuel Pump Relay Terminals 2, 3 And Ground
    G02369851Courtesy of NISSAN MOTOR CO., U.S.A.
  3. DETECT MALFUNCTIONING PART 

    Check the following

    • Fuse block (J/B) No. 1 connector M1
    • Fuse block (J/B) No. 2 connectors M143, M145
    • 15A fuse
    • Harness for open or short between fuse and fuel pump relay
      1. Repair open circuit or short to ground or short to power in harness or connectors.
  4. 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.
      Fig 4: Locating Fuel Level Sensor Unit And Fuel Pump Harness Connector
      G02369852Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Disconnect dropping resistor harness connector.
      Fig 5: Locating Dropping Resistor Harness Connector
      G02369853Courtesy of NISSAN MOTOR CO., U.S.A.
    4. Check harness continuity between the following;

      fuel pump relay terminal 5 and fuel pump terminal 3,

      fuel pump terminal 1 and dropping resistor terminal 2,

      dropping resistor terminal 1 and ground.

      Refer to WIRING DIAGRAM .

      1. Continuity should exist. 
    5. Also check harness for short to ground and short to power.

    OK or NG 

    1. OK: GO TO  6.
    2. NG: GO TO 5.
  5. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors B211, M141
    • Harness connectors B63, B263
    • Fuse block (J/B) No. 2 connector M143
    • Harness for open or short between fuel pump relay and fuel pump
    • Harness for open or short between fuel pump and dropping resistor
    • Harness for open or short between dropping resistor and ground
      1. Repair open circuit or short to ground or short to power in harness or connectors.
  6. CHECK FUEL PUMP RELAY OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Disconnect ECM harness connector.
    2. Check harness continuity between ECM terminal 113 and fuel pump relay terminal 1. Refer to WIRING DIAGRAM .
      1. Continuity should exist. 
    3. Also check harness for short to ground and short to power.

    OK or NG 

    1. OK: GO TO  8.
    2. NG: GO TO 7.
  7. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors M135, F105
    • Fuse block (J/B) No. 2 connector M143
    • Harness for open or short between ECM and fuel pump relay
      1. Repair open circuit or short to ground or short to power in harness or connector
  8. CHECK DROPPING RESISTOR 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK: GO TO 9.
    2. NG: Replace dropping resistor.
  9. CHECK FUEL PUMP RELAY 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK: GO TO 10.
    2. NG: Replace fuel pump relay.
  10. CHECK FUEL PUMP 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK: GO TO 11.
    2. NG: Replace fuel pump.
  11. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    1. : INSPECTION END