UART Communication Line Circuit Check

WARNING: This page is about a different car, the 2004 Nissan Murano. However, it is still accessible from the selected car via links, so may be relevant.

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: Reference Value Chart
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Fig 2: Checking Signal Between Driver Seat Control Unit Connector And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
1. OK: GO TO 2.
2. NG: Check the following.
  - When voltage waveform does not appear with a constant voltage (approx. 5V), replace driver seat control unit.
  - When voltage waveform does not appear with a constant voltage (approx. 0V), replace automatic driver seat control unit.
CHECK UART LINE INPUT/OUTPUT SIGNAL 2
Check signal between automatic driver positioner control unit connector ground, with oscilloscope.

Fig 3: Reference Value Chart
Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 4: Checking Signal Between Automatic Driver Positioner Control Unit Connector Ground
Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG
1. OK: GO TO 3.
2. NG: Check the following.
  - When voltage waveform does not appear with a constant voltage (approx. 5V), replace automatic drive positioner control unit.
  - When voltage waveform does not appear with a constant voltage (approx. 0V), replace driver seat control unit.
CHECK UART LINE HARNESS
1. Disconnect driver seat control unit connector and automatic drive positioner control unit connector.
2. Check continuity between driver seat control unit connector B303 terminal 1 (Y/W), 17 (Y/L) and automatic drive positioner connector M19 terminal 10 (R), 26 (R/G).
  1 (Y/W) -10 (R): Continuity should exist.
  
  17 (Y/L) - 26 (R/G): Continuity should exist.
3. Check continuity between driver seat control unit connector B303 terminal 1 (Y/W), 17 (Y/L) and ground.
  1 (Y/W) - Ground: Continuity should not exist.
  
  17 (Y/L) - Ground: Continuity should not exist.
  
  Fig 5: Checking Continuity Between Driver Seat Control Unit Connector And Automatic Drive Positioner Connector, And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
1. OK: GO TO 4.
2. NG: Repair or replace harness between driver seat control unit and automatic drive positioner control unit.
CHECK DRIVER SEAT CONTROL UNIT
Dose the automatic drive positioner operate, when the driver control unit exchanged?

OK or NG
1. OK: Replace automatic drive positioner control unit.
2. NG: Replace driver seat control unit.