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Home >> Nissan-Datsun >> 2004 >> Sentra SE-R >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Qr25DE >> 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.

      Voltage: Battery voltage 

    OK or NG 

    1. OK: GO TO  4.
    2. NG: GO TO 3.
      Fig 1: Checking ECM Power Supply Circuit-I
      G00776874Courtesy of NISSAN MOTOR CO., U.S.A.
  3. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors M19, E108
    • Harness connectors E10, F48
    • Fuse block (J/B) connector M1
    • 10A fuse
    • Harness for open or short between ECM and fuse
      1. Repair harness or connectors.
  4. CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT-I 
    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 .

      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 M58, F26
    • 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
      G00776875Courtesy of NISSAN MOTOR CO., U.S.A.
    2. Check voltage between ECM relay terminals 1, 6 and ground with CONSULT-II or tester.
      Fig 3: Checking Voltage Between ECM Relay Terminals 1, 6 & Ground
      G00776876Courtesy of NISSAN MOTOR CO., U.S.A.

      Voltage: Battery voltage 

    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
    • Fuse and fusible link box connectors E22, E24
    • 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 .

      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.

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

      Fig 4: Checking Voltage Between ECM Terminals 119, 120 & Ground
      G00776877Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO  14.

    NG (Battery voltage does not exist.): GO TO 10.

    NG (Battery voltage exists for more than a few seconds.): GO TO  13.

  10. CHECK ECM POWER SUPPLY CIRCUIT-IV 
    1. Disconnect ECM relay.
      Fig 5: Disconnecting ECM Relay
      G00776878Courtesy of NISSAN MOTOR CO., U.S.A.
    2. Check voltage between ECM relay terminal 3 and ground with CONSULT-II or tester.

      Voltage: Battery voltage 

      3. Fig 6: Checking Voltage Between ECM Relay Terminal 3 & Ground
      G00776879Courtesy 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 following.

    • Harness connectors E10, F48
    • Fuse and fusible link box connectors E22, E24
    • Harness for open or short between ECM relay and harness connector F48
      1. Repair open circuit or short to ground or short to power in harness or connectors.
  12. CHECK HARNESS CONTINUITY BETWEEN ECM RELAY AND ECM FOR OPEN AND SHORT 
    1. Disconnect ECM harness connector.
    2. Check harness continuity between ECM terminals 119, 120 and ECM relay terminal 5. Refer to WIRING DIAGRAM .

      Continuity should exist. 

    3. 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.
  13. CHECK ECM RELAY 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK: GO TO 14.
    2. NG: Replace ECM relay.
  14. 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 1, 115, 116 and engine ground. Refer to WIRING DIAGRAM .

      Continuity should exist. 

    4. Also check harness for short to power.

    OK or NG 

    1. OK: GO TO  16.
    2. NG: GO TO 15.
  15. DETECT MALFUNCTIONING PART 

    Check the following.

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

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    1. INSPECTION END 
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