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Home >> Infiniti >> 2005 >> Q45 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Introduction >> 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  14.
    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
    G02372654Courtesy of NISSAN MOTOR CO., U.S.A.
  3. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors E32, F32
    • Fuse block (J/B) No. 1 connector M1
    • Fuse block (J/B) No. 2 connectors M143, E215
    • 15A 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.
    • CHECK GROUND CONNECTIONS 
      1. Turn ignition switch OFF.
      2. Loosen and retighten three ground screws on the body. Refer to "GROUND INSPECTION ".
        Fig 2: Identifying Connections Ground
        G02372655Courtesy of NISSAN MOTOR CO., U.S.A.

      OK or NG 

      1. OK: GO TO 5.
      2. NG: Repair or replace ground connections.
    • 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  9.
      2. NG: GO TO 6.
    • DETECT MALFUNCTIONING PART 

      Check the following.

      • Harness connectors F32, E32
      • Harness for open or short between ECM and ground
        1. Repair open circuit or short to power in harness or connectors.
    • CHECK ECM POWER SUPPLY CIRCUIT-II 
      1. Disconnect ECM relay.
        Fig 3: Disconnecting ECM Relay
        G02372656Courtesy of NISSAN MOTOR CO., U.S.A.
      2. Check voltage between ECM relay terminals 2, 5 and ground with CONSULT-II or tester.
        1. Voltage: Battery voltage 

      OK or NG 

      1. OK: GO TO  11.
      2. NG: GO TO 8.
      Fig 4: Checking Voltage Between ECM Relay Terminals 2, 5 And Ground With CONSULT-II
      G02372657Courtesy of NISSAN MOTOR CO., U.S.A.
    • 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
        1. Repair open circuit or short to ground or short to power in harness or connectors.
    • CHECK OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
      1. Check harness continuity between ECM terminal 111 and ECM relay terminal 1. 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: GO TO 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
        1. Repair open circuit or short to ground or short to power in harness or connectors.
    • CHECK ECM RELAY 

      Refer to "COMPONENT INSPECTION ".

      OK or NG 

      1. OK: GO to " IGNITION SIGNAL  "  .
      2. NG: Replace ECM relay.
    • CHECK ECM POWER SUPPLY CIRCUIT-III 
      1. Turn ignition switch ON and then OFF.
      2. 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 Terminals 119, 120 And Ground With CONSULT-II
        G02372658Courtesy of NISSAN MOTOR CO., U.S.A.

      OK or NG 

      1. OK: GO TO 18.
      2. NG (Battery voltage does not exist.): GO TO 13.
      3. NG (Battery voltage exists for more than a few seconds.): GO TO  12.
    • CHECK ECM POWER SUPPLY CIRCUIT-IV 
      1. Disconnect ECM relay.
        Fig 6: Identifying ECM Relay
        G02372659Courtesy of NISSAN MOTOR CO., U.S.A.
      2. Check voltage between ECM relay terminal 7 and ground with CONSULT-II or tester.
        1. Voltage: Battery voltage 

      OK or NG 

      1. OK: GO TO  17.
      2. NG: GO TO 14.
      Fig 7: Checking Voltage Between ECM Relay Terminal 7 And Ground With CONSULT-II
      G02372660Courtesy of NISSAN MOTOR CO., U.S.A.
    • DETECT MALFUNCTIONING PART 

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

      1. Repair open circuit or short to ground or short to power in harness or connectors.
    • CHECK ECM POWER SUPPLY CIRCUIT-V 
      1. Disconnect ECM harness connector.
      2. Check harness continuity between ECM terminals 119, 120 and ECM relay terminal 6. 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  19.
      2. NG: GO TO 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
        1. Repair open circuit or short to ground or short to power in harness or connectors.
    • CHECK ECM RELAY 

      Refer to "COMPONENT INSPECTION ".

      OK or NG 

      1. OK: GO TO 18.
      2. NG: Replace ECM relay.
    • CHECK GROUND CONNECTIONS 
      1. Turn ignition switch OFF.
      2. Loosen and retighten three ground screws on the body. Refer to "GROUND INSPECTION ".
        Fig 8: Identifying Connections Ground
        G02372661Courtesy of NISSAN MOTOR CO., U.S.A.

      OK or NG 

      1. OK: GO TO 19.
      2. NG: Repair or replace ground connections.
    • 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  23.
      2. NG: GO TO 20.
    • DETECT MALFUNCTIONING PART 

      Check the following.

      • Harness connectors F32, E32
      • Harness for open or short between ECM and ground
        1. Repair open circuit or short to power in harness or connectors.
    • CHECK INTERMITTENT INCIDENT 

      Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

      1. INSPECTION END 
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