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Home >> Infiniti >> 2004 >> M45 >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> Power Supply And Ground Circuit >> Diagnostic Procedure
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Diagnostic Procedure

  1. Inspection Start 
    1. Start engine.
    2. Is engine running? 
    3. Yes or No 
    1. Yes: GO TO  12.
    2. No: GO TO 2.
  2. Check ECM Power Supply Circuit-I 
    1. Turn ignition switch OFF and then ON.
    2. Check voltage between ECM terminal 53 and ground with CONSULT-II or tester.
    1. Voltage: Battery voltage 
    2. OK or NG 
    3. OK: GO TO  4.
    4. NG: GO TO 3.
  3. Detect Malfunctioning Part 

    Check the following.

    • Harness connectors E33, F33
    • Fuse block (J/B) No. 1 connector M1
    • Fuse block (J/B) No. 2 connector M143, E215
    • Joint connector-19
    • 15A fuse
    • Harness for open or short between ECM and fuse

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

  4. Check Ground Connections 
    1. Turn ignition switch OFF.
    2. Loosen and retighten two ground screws.

      Refer to GROUND INSPECTION .

      Fig 1: Identifying Engine Ground Wires
      G00795637Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 5.
    2. NG: Repair or replace ground connections.

  5. Check ECM Ground Circuit For Open And Short-I 
    1. Disconnect ECM harness connector.
    2. Check harness continuity between ECM terminals 156, 159, 165, 168 and ground.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    3. Also check harness for short to power.
    1. OK or NG 
    2. OK: GO TO  7.
    3. NG: GO TO 6.
  6. Detect Malfunctioning Part 

    Check the following.

    • Joint connector-29
    • Harness for open or short between ECM and ground

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

  7. Check Power Supply-II 
    1. Disconnect ECM relay.
      Fig 2: Locating & Disconnecting ECM Relay
      G00795638Courtesy of NISSAN MOTOR CO., U.S.A.
    2. Check voltage between ECM relay terminals 2, 5 and ground with CONSULT-II or tester.
      3. Fig 3: Checking ECM Relay Terminal Voltage
      G00795639Courtesy of NISSAN MOTOR CO., U.S.A.
    1. Voltage :Battery voltage 
    2. OK or NG 
    3. OK: GO TO  9.
    4. NG: GO TO 8.
  8. Detect Malfunctioning Part 

    Check the following.

    • 10A fuse
    • 20A fuse
    • Fuse block (J/B) No. 2 connector E215
    • Fuse, fusible link and relay block (J/B) connector E3
    • Harness for open or short between ECM relay and battery

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

  9. Check Output Signal Circuit For Open And Short 
    1. Check harness continuity between ECM terminal 42 and ECM relay terminal 1.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    2. Also check harness for short to ground and short to power.
    1. OK or NG 
    2. OK: GO TO  11.
    3. NG: GO TO 10.
  10. 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 relay and ECM

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

  11. Check ECM Relay 

    Refer to COMPONENT INSPECTION .

    1. OK or NG 
    2. OK: Go to IGNITION SIGNAL .
    3. NG: Replace ECM relay.
  12. Check ECM Power Supply Circuit-III 
    1. Turn ignition switch ON and then OFF.
    2. Check voltage between ECM terminals 12, 163, 166 and ground with CONSULT-II or tester.

    Voltage: After turning ignition switch OFF, battery voltage will exist for a few seconds, then drop approximately 0V. 

    1. OK or NG 
    2. OK: GO TO  18.
    3. NG (Battery voltage does not exist.): GO TO 13.
    4. NG (Battery voltage exists for more than a few seconds.): GO TO  15.
  13. Check ECM Power Supply Circuit-IV 
    1. Disconnect ECM relay.
    2. Check voltage between ECM relay terminal 7 and ground with CONSULT-II or tester.
      3. Fig 4: Checking ECM Relay Terminal 7 Voltage & Ground
      G00795642Courtesy of NISSAN MOTOR CO., U.S.A.

    Voltage: Battery voltage 

    1. OK or NG 
    2. OK: GO TO  15.
    3. NG: GO TO 14.
  14. Detect Malfunctioning Part 

    Check harness for open or short between ECM relay and 10A fuse

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

  15. Check Harness Continuity Between ECM Relay And ECM For Open And Short 
    1. Disconnect ECM harness connector.
    2. Check harness continuity between ECM terminals and ECM relay terminals as follows.

      Refer to WIRING DIAGRAM .

      Fig 5: Identifying ECM & ECM Relay Terminal Information
      G00795643Courtesy of NISSAN MOTOR CO., U.S.A.

      Continuity should exist. 

    3. Also check harness for short to ground and short to power.
    1. OK or NG 
    2. OK: GO TO  17.
    3. NG: GO TO 16.
  16. 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 ECM relay

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

  17. Check ECM Relay 

    Refer to COMPONENT INSPECTION .

    1. OK or NG 
    2. OK: GO TO 18.
    3. NG: Replace ECM relay.
  18. Check Ground Connections 
    1. Turn ignition switch OFF.
    2. Loosen and retighten two ground screws.
      Fig 6: Locating Engine Ground
      G00795644Courtesy of NISSAN MOTOR CO., U.S.A.

      Refer to GROUND INSPECTION .

    1. OK or NG 
    2. OK: GO TO 19.
    3. NG: Repair or replace ground connections.
  19. Check ECM Ground Circuit For Open And Short-II 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between ECM terminals 156, 159, 165, 168 and ground.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    4. Also check harness for short to power.
    1. OK or NG 
    2. OK: GO TO  21.
    3. NG: GO TO 20.
  20. Detect Malfunctioning Part 

    Check the following.

    • Joint connector-29
    • Harness for open or short between ECM and ground
    1. : Repair open circuit or short to power in harness or connectors.
  21. Check Intermittent Incident 

    Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

    1. : INSPECTION END 
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