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UART Communication Line Circuit Inspection

WARNING: This page is about a different car, the 2005 Infiniti QX56. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK UART LINE INPUT/OUTPUT SIGNAL 1 
    1. Turn ignition switch OFF.
    2. Check signal between driver seat control unit connector and ground, with oscilloscope.
    Fig 1: Driver Seat Control Unit Connector P2 Terminal 17 And Ground Signal Specifications
    G02384242Courtesy of NISSAN MOTOR CO., U.S.A.
    Fig 2: Checking Signal Between Driver Seat Control Unit Connector And Ground With Oscilloscope
    G02384243Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG

    • OK: GO TO 2.
    • NG: Check the following.
      • When voltage wave form does not appear with a constant voltage (approx. 5V), replace driver seat control unit.
      • When voltage wave form does not appear with a constant voltage (approx. 0V), replace automatic driver seat control unit.
  2. CHECK UART LINE INPUT/OUTPUT SIGNAL 2 

    Check signal between automatic drive positioner control unit connector ground, with oscilloscope.

    Fig 3: Automatic Drive Positioner Control Unit Connector M33 Terminal 10 And Ground Signal Specifications
    G02384244Courtesy of NISSAN MOTOR CO., U.S.A.
    Fig 4: Checking Signal Between Automatic Drive Positioner Control Unit Connector Ground With Oscilloscope
    G02384245Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG

    • OK: GO TO 3.
    • NG: Check the following.
      • When voltage wave form does not appear with a constant voltage (approx. 5V), replace automatic drive positioner control unit.
      • When voltage wave form does not appear with a constant voltage (approx. 0V), replace driver seat control unit.
  3. CHECK UART LINE HARNESS 
    1. Disconnect driver seat control unit and automatic drive positioner control unit.
    2. Check continuity between driver seat control unit connector P2 terminals 1, 17 and automatic drive positioner connector M33 terminals 10, 26.
      • 1 (L) - 10 (L): Continuity should exist. 
      • 17 (W) - 26 (W): Continuity should exist. 
    3. Check continuity between driver seat control unit connector P2 terminals 1, 17 and ground.
      • 1 (L) - Ground: Continuity should not exist. 
      • 17 (W) - Ground: Continuity should not exist. 

    OK or NG

    • OK: GO TO 4.
    • NG: Repair or replace harness.
    Fig 5: Checking Continuity Between Driver Seat Control Unit Connector P2 Terminals 1, 17 And Automatic Drive Positioner Connector M33 Terminals 10 And 26
    G02384246Courtesy of NISSAN MOTOR CO., U.S.A.
  4. CHECK DRIVER SEAT CONTROL UNIT 

    Does the automatic drive positioner operate when the driver seat control unit is exchanged?

    OK or NG

    • OK: Replace driver seat control unit.
    • NG: Replace automatic drive positioner control unit.
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