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Home >> Nissan-Datsun >> 2004 >> Sentra Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - QG18DE >> Power Supply Circuit For ECM >> Diagnostic Procedure
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Diagnostic Procedure

  1. INSPECTION START 

    Start engine.

    Is engine running? 

    Yes or No 

    1. Yes: GO TO  9.
    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 109 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 1: Checking Voltage Between ECM Terminal 109 And Ground With Consult-II Or Tester
    G00774775Courtesy of NISSAN MOTOR CO., U.S.A.
  3. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors E10, F48
    • Harness connectors M19, E108
    • Fuse block (J/B) connector M1
    • 10A fuse
    • Harness for open or short between ECM and fuse
    1. : Repair open circuit or short to ground or short to power in harness or connectors.
  4. CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between ECM terminals 1, 115, 116, and engine ground.

      Refer to WIRING DIAGRAM .

      1. Continuity should exist. 
    4. Also check harness for 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 F26, M58
    • Harness for open or short between ECM and ground
    1. : Repair open circuit or short to power in harness or connectors.
  6. CHECK ECM POWER SUPPLY CIRCUIT-II 
    1. Disconnect ECM relay.
      Fig 2: Disconnecting ECM Relay
      G00774776Courtesy of NISSAN MOTOR CO., U.S.A.
    2. Check voltage between ECM relay terminals 1, 6 and ground with CONSULT-II or tester.
      1. Voltage: Battery voltage 

    OK or NG 

    1. OK: GO TO  8.
    2. NG: GO TO 7.
    Fig 3: Checking Voltage Between ECM Relay Terminals 1, 6 And Ground With Consult-II Or Tester
    G00774777Courtesy of NISSAN MOTOR CO., U.S.A.
  7. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors E10, F48
    • Fuse and fusible link box connectors E22, E24
    • 10A fuse
    • 15A fuse
    • Harness for open or short between ECM relay and battery
    1. : Repair open circuit or short to ground or short to power in harness or connectors.
  8. CHECK ECM RELAY OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT-I 
    1. Check harness continuity between ECM terminal 111 and ECM relay terminal 2.
      1. Continuity should exist. 
    2. Also check harness for short to ground and short to power.

    OK or NG 

    1. OK: Go to IGNITION SIGNAL .
    2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
  9. CHECK ECM POWER SUPPLY CIRCUIT-III 
    1. Stop engine.
    2. Turn ignition switch ON and then OFF.
    3. Check voltage between ECM terminals 119, 120 and ground with CONSULT-II or tester.
      1. Voltage: After turning ignition switch OFF, battery voltage will exist for a few seconds, then drop to approximately 0V. 

    OK or NG 

    1. OK: GO TO  15.
    2. NG (Battery voltage does not exist.): GO TO 10.
    3. NG (Battery voltage exists for more than a few seconds.): GO TO  12.
    Fig 4: Checking Voltage Between ECM Terminals 119, 120 And Ground With Consult-II Or Tester
    G00774778Courtesy of NISSAN MOTOR CO., U.S.A.
  10. CHECK ECM POWER SUPPLY CIRCUIT-IV 
    1. Disconnect ECM harness connector.
    2. Disconnect ECM relay.
      Fig 5: Disconnecting ECM Relay
      G00774779Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Check voltage between ECM relay terminal 3 and ground with CONSULT-II or tester.
      1. Voltage: Battery voltage 
      Fig 6: Checking Voltage Between ECM Relay Terminal 3 And Ground With Consult-II Or Tester
      G00774780Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO  12.
    2. NG: GO TO 11.
  11. DETECT MALFUNCTIONING PART 

    Check the harness for open or short between ECM relay and harness connector F48.

    1. : Repair harness or connectors.
  12. CHECK ECM POWER SUPPLY CIRCUIT-V 
    1. Check harness continuity between ECM terminals 119, 120 and ECM relay terminal 5.

      Refer to WIRING DIAGRAM .

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

    OK or NG 

    1. OK: GO TO 13.
    2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
    Fig 7: Checking Harness Continuity Between ECM Terminals 119, 120 And ECM Relay Terminal 5
    G00774781Courtesy of NISSAN MOTOR CO., U.S.A.
  13. CHECK ECM RELAY OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT-II 
    1. Check harness continuity between ECM terminal 111 and ECM relay terminal 2. Refer to WIRING DIAGRAM .
      1. Continuity should exist. 
    2. Also check harness for short to ground and short to power.

    OK or NG 

    1. OK: GO TO 14.
    2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
  14. CHECK ECM RELAY 
    1. Apply 12V direct current between ECM relay terminals 1 and 2.
    2. Check continuity between ECM relay terminals 3 and 5, 6 and 7.
      Fig 8: Terminals Continuity Chart
      G00774782Courtesy of NISSAN MOTOR CO., U.S.A.
      Fig 9: Checking Continuity Between ECM Relay Terminals 3 And 5, 6 And 7
      G00774783Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 15.
    2. NG: Replace ECM relay.
  15. CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between ECM terminals 1, 115, 116, and engine ground.

      Refer to WIRING DIAGRAM .

      1. Continuity should exist. 
    4. Also check harness for short to power.

    OK or NG 

    1. OK: GO TO  17.
    2. NG: GO TO 16.
  16. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors F26, M58
    • Harness for open or short between ECM and ground
    1. : Repair open circuit or short to power in harness or connectors.
  17. CHECK INTERMITTENT INCIDENT 

    Perform TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

    1. INSPECTION END
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