UART Communication Line Circuit Inspection

WARNING: This page is about a different car, the 2004 Nissan Quest. 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: Terminal Signal Table
Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 2: Checking Signal Between Driver Seat Control Unit Connector & Ground
Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG
1. OK: GO TO 2.
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.
CHECK UART LINE INPUT/OUTPUT SIGNAL 2
Check signal between automatic front positioner control unit connector ground, with oscilloscope.

Fig 3: Terminal Signal Table
Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 4: Checking Signal Between Automatic Front 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 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.
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 terminal 1 (R), 17 (R/W) and automatic drive positioner connector M41 terminal 10 (R), 26 (R/W).
  1. 1 (R) -10 (R): Continuity should exist.
  2. 17 (R/W) - 26 (R/W): Continuity should exist.
3. Check continuity between driver seat control unit connector P2 terminal 1 (R/B), 17 (GR) and ground.
  1. 1 (R) - Ground: Continuity should not exist.
  2. 17 (R/W) - Ground: Continuity should not exist.
  OK or NG
  1. OK: GO TO 4.
  2. NG: Repair or replace harness.
  Fig 5: Checking Continuity Between Driver Seat Control Unit Connector & Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK DRIVER SEAT CONTROL UNIT
Does the automatic drive positioner operate when the driver seat control unit is exchanged?

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

Refer to ACCELERATOR CONTROL SYSTEM . and BRAKE PEDAL FREE PLAY . ".