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Home >> Infiniti >> 2004 >> FX45 >> Repair and Diagnosis >> Electrical >> Gauges >> Combination Meters >> Communication Line Inspection

Communication Line Inspection

  1. Check Connector 

    Check combination meter, unified meter and A/C amp. and terminals (combination meter-side, unified meter and A/C amp. side, and harness side) for looseness or bent terminals.

    OK or NG

    1. OK: GO TO 2.
    2. NG: Repair terminal or connector.

  2. Check Meter/Gauges Visually 

    Does the pointer on the meter/gauge fluctuate at the engine start?

    Is the fluctuation acceptable?

    1. YES: GO TO 3.
    2. NO: GO TO  6 .

  3. Check Continuity Communication Circuit (RX: Combination Meter) 
    1. Turn ignition switch OFF.
    2. Disconnect the combination meter connector and unified meter and A/C amp. connector.
    3. Check continuity between combination meter harness connector M20 terminal 13 (L/B) and unified meter and A/C amp. harness connector M55 terminal 19 (L/B).
      Fig 1: Checking Circuit Continuity
      G02493801Courtesy of NISSAN MOTOR CO., U.S.A.

      Continuity should exist  .

    4. Check continuity between combination meter harness connector M20 terminal 13 (L/B) and ground.

      Continuity should not exist  .

    OK or NG

    1. OK: GO TO 4.
    2. NG: Repair harness or connector.

  4. Check Voltage Of Unified Meter And A/C Amp  .
    1. Connect unified meter and A/C amp. connector.
    2. Turn ignition switch ON.
    3. Check voltage between combination meter harness connector M20 terminal 13 (L/B) and ground.
      Fig 2: Checking Voltage At Combination Meter Harness Connector M20 Terminal 13
      G02493802Courtesy of NISSAN MOTOR CO., U.S.A.

      Approximately 5V 

    OK or NG

    1. OK: GO TO 5.
    2. NG: Replace unified meter and A/C amp. Refer to REMOVAL AND INSTALLATION OF UNIFIED METER AND A/C AMP.  .

  5. Check Voltage Signal Of Combination Meter 
    1. Turn ignition switch OFF and connect combination meter connector.
    2. Turn ignition switch ON.
    3. Check voltage signal between combination meter harness connector M20 terminal 13 (L/B) and ground with simple oscilloscope of CONSULT-II.
      Fig 3: Voltage Signal At Combination Meter Connector M20 Terminal 13 - Using Oscilloscope
      G02493803Courtesy of NISSAN MOTOR CO., U.S.A.
      Fig 4: Voltage Signal At Combination Meter Connector M20 Terminal 13 - Using DVOM
      G02493804Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG

    1. OK: Replace unified meter and A/C amp. Refer to REMOVAL AND INSTALLATION OF UNIFIED METER AND A/C AMP  .
    2. NG: Replace combination meter.

  6. Check Continuity Communication Circuit (TX: Combination Meter) 
    1. Turn ignition switch OFF.
    2. Disconnect combination meter connector and unified meter and A/C amp. connector.
    3. Check continuity between combination meter harness connector M20 terminal 14 (PU) and unified meter and A/C amp. harness connector M55 terminal 9 (PU).
      Fig 5: Circuit Test Combination Meter Connector M20 Terminal 14 To Unified Meter And A/C Amp. Connector M55 Terminal 9
      G02493805Courtesy of NISSAN MOTOR CO., U.S.A.

      Continuity should exist  .

    4. Check continuity between combination meter harness connector M20 terminal 14 (PU) and ground.

      Continuity should not exist  .

    OK or NG

    1. OK: GO TO 7.
    2. NG: Repair harness or connector.

  7. Check Voltage Of Combination Meter 
    1. Connect combination meter connector.
    2. Turn ignition switch ON.
    3. Check voltage between unified meter and A/C amp. harness connector M55 terminal 9 (PU) and ground.
      Fig 6: Checking Voltage At Unified Meter And A/C Amp. Harness Connector M55 Terminal 9
      G02493806Courtesy of NISSAN MOTOR CO., U.S.A.

      Approximately 5V 

    OK or NG

    1. OK: GO TO 8.
    2. NG: Replace combination meter.

  8. Check Voltage Signal Of Unified Meter And A/C Amp 
    1. Turn ignition switch OFF and connect unified meter and A/C amp. connector.
    2. Turn ignition switch ON.
    3. Check voltage signal between combination meter harness connector M20 terminal 14 (PU) and ground with simple oscilloscope of CONSULT-II.
      Fig 7: Voltage Signal At Combination Meter Harness Connector M20 Terminal 14 Using Oscilloscope
      G02493807Courtesy of NISSAN MOTOR CO., U.S.A.
      Fig 8: Voltage Signal At Combination Meter Harness Connector M20 Terminal 14 Using DVOM
      G02493808Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG

    1. OK: Replace combination meter.
    2. NG: Replace unified meter and A/C amp. Refer to REMOVAL AND INSTALLATION OF UNIFIED METER AND A/C AMP.  .

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