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Home >> Nissan-Datsun >> 2005 >> Sentra SE-R >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Introduction (Qr25DE) >> Power Supply And Ground Circuit >> Diagnostic Procedure
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Diagnostic Procedure

  1. INSPECTION START 

    Start engine.

    Is engine running? 

    Yes or No 

    1. Yes : GO TO  10.
    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 
      3. Fig 1: Checking Voltage Between ECM Connector Terminal 109 And Ground
      G02450813Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK : GO TO  4.
    2. NG : GO TO 3.
  3. DETECT MALFUNCTIONING PART 

    Check the following.

    • Fuse block (J/B) connector M1
    • 10A fuse
    • Harness connectors M19, E108
    • Harness connectors E10, F48
    • 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 GROUND CONNECTIONS 
    1. Turn ignition switch OFF.
    2. Loosen and retighten two ground screws on the body.

      Refer to "GROUND INSPECTION ".

      Fig 2: Checking ECM Ground Connections
      G02450814Courtesy 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 1, 115, 116 and ground.

      Refer to WIRING DIAGRAM .

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

    OK or NG 

    1. OK : GO TO 6.
    2. NG : Repair open circuit or short to power in harness or connectors.
  6. CHECK ECM POWER SUPPLY CIRCUIT-II 
    1. Disconnect ECM relay.
      Fig 3: Locating ECM Relay
      G02450815Courtesy 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 
      Fig 4: Checking Voltage Between ECM Relay Connector Terminals 1, 6 And Ground
      G02450816Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

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

    Check the following.

    • Harness connectors E10, F48
    • 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 OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    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 9.
    2. NG : Repair open circuit or short to ground or short to power in harness or connectors.
  9. CHECK ECM RELAY 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK : Go to "IGNITION SIGNAL ".
    2. NG : Replace ECM relay.
  10. CHECK ECM POWER SUPPLY CIRCUIT-III 
    1. Stop engine and wait at least 10 seconds.
    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 approximately 0V. 
      Fig 5: Checking Voltage Between ECM Connector Terminals 119, 120 And Ground
      G02450817Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK : GO TO  15.
    2. NG (Battery voltage does not exist.) : GO TO 11.
    3. NG (Battery voltage exists for more than a few seconds.) : GO TO  13.
  11. CHECK ECM POWER SUPPLY CIRCUIT-IV 
    1. Disconnect ECM relay.
      Fig 6: Locating ECM Relay
      G02450818Courtesy of NISSAN MOTOR CO., U.S.A.
    2. Check voltage between ECM relay terminal 3 and ground with CONSULT-II or tester.
      1. Voltage: Battery voltage 
      Fig 7: Checking Voltage Between ECM Relay Connector Terminal 3 And Ground
      G02450819Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK : GO TO  13.
    2. NG : GO TO 12.
  12. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors E10, F48
    • 10A 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.
  13. CHECK ECM POWER SUPPLY CIRCUIT-V 
    1. Disconnect ECM harness connector.
    2. Check harness continuity between ECM terminals 119, 120 and ECM relay terminal 5.

      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 14.
    2. NG : Repair open circuit or short to ground or short to power in harness or connectors.
  14. CHECK ECM RELAY 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK : GO TO 15.
    2. NG : Replace ECM relay.
  15. CHECK GROUND CONNECTIONS 
    1. Loosen and retighten two ground screws on the body.

      Refer to "GROUND INSPECTION ".

      Fig 8: Checking ECM Ground Connections
      G02450820Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK : GO TO 16.
    2. NG : Repair or replace ground connections.
  16. CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT-II 
    1. Disconnect ECM harness connector.
    2. Check harness continuity between ECM terminals 1, 115, 116 and ground.

      Refer to WIRING DIAGRAM .

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

    OK or NG 

    1. OK : GO TO 17.
    2. NG : Repair open circuit or short to power in harness or connectors.
  17. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    1. : INSPECTION END 
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