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Home >> Nissan-Datsun >> 2004 >> Frontier Desert Runner SE >> Repair and Diagnosis >> Engine Performance >> Engine Control System - VG33E >> Basic Service Procedure >> 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  6.
    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 24 and engine 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 24 And Engine Ground
    G00742636Courtesy of NISSAN MOTOR CO., U.S.A.
  3. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors E43, M65
    • Harness connectors M5, F27
    • Fuse block (J/B) connector E49
    • 10A fuse
    • Harness for open or short between ECM and fuse
    1. : Repair harness or connectors.
  4. CHECK ECM GROUND CIRCUIT-I FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between ECM terminals 10, 19, 25, 32, 116, 124 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  15.
    2. NG : GO TO 5.
  5. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness for open between ECM and engine ground
    1. : Repair open circuit or short to power in harness or connectors.
  6. CHECK ECM POWER SUPPLY CIRCUIT-II 
    1. Stop engine.
    2. Check voltage between ECM terminal 80 and engine ground with CONSULT-II or tester.

      Voltage: Battery voltage 

    OK or NG 

    1. OK : GO TO  8.
    2. NG : GO TO 7.
    Fig 2: Checking Voltage Between ECM Terminal 80 And Engine Ground
    G00742637Courtesy of NISSAN MOTOR CO., U.S.A.
  7. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors M81, F36
    • Fuse block (J/B) connector M27
    • 10A fuse
    • Harness for open or short between ECM and fuse
    1. : Repair harness or connectors.
  8. CHECK ECM POWER SUPPLY CIRCUIT-III 
    1. Turn ignition switch ON and then OFF.
    2. Check voltage between ECM terminals 67, 72, 117 and engine ground with CONSULT-II or tester.

      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  14.
    2. NG (Battery voltage does not exist): GO TO 9.
    3. NG (Battery voltage exists for more than a few seconds): GO TO  13.
    Fig 3: Checking Voltage Between ECM Terminals 67, 72, 117 And Engine Ground
    G00742638Courtesy of NISSAN MOTOR CO., U.S.A.
  9. CHECK ECM POWER SUPPLY CIRCUIT-IV 
    1. Disconnect ECM relay.
      Fig 4: Locating ECM Relay
      G00742639Courtesy of NISSAN MOTOR CO., U.S.A.
    2. Check voltage between terminals 2, 5 and engine ground with CONSULT-II or tester.

    Voltage: Battery voltage 

    OK or NG 

    1. OK: GO TO  11.
    2. NG: GO TO 10.
    Fig 5: Checking Voltage Between ECM Terminals 2, 5 And Engine Ground
    G00742640Courtesy of NISSAN MOTOR CO., U.S.A.
  10. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness for open or short between ECM relay and harness connectors M59, F27
    1. : Repair open circuit or short to ground or short to power in harness or connectors.
  11. CHECK ECM OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Disconnect ECM harness connector.
    2. Check harness continuity between ECM terminal 4 and ECM relay terminal 1.

      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 12.
    2. NG: 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. Check harness continuity between ECM terminals 67, 72, 117 and ECM relay terminal 3.

      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 13.
    2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
  13. CHECK ECM RELAY 
    1. Apply 12V direct current between relay terminals 1 and 2.
    2. Check continuity between relay terminals 3 and 5.

      12V (1 - 2) applied: Continuity exists. 

      No voltage applied: No continuity 

    OK or NG 

    1. OK: GO TO 14.
    2. NG: Replace ECM relay.
    Fig 6: Identifying ECM Relay Terminals
    G00742641Courtesy of NISSAN MOTOR CO., U.S.A.
  14. CHECK ECM GROUND CIRCUIT-II FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between ECM terminals 10, 19, 25, 32, 116, 124 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 15.
    2. NG: GO TO  5.
  15. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    1. : INSPECTION END 
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