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Home >> Acura >> 2007 >> RDX >> Repair and Diagnosis >> Body & Frame >> Seats >> Driver Position Memory System (DPMS) >> DTC Troubleshooting >> DTC B1843: Power Seat Control Unit Lost Communication with Power Mirror Control Unit (UART line)

DTC B1843: Power Seat Control Unit Lost Communication with Power Mirror Control Unit (UART line)

NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A (see TROUBLESHOOTING - B-CAN SYSTEM DIAGNOSIS TEST MODE A ).
  1. Clear the DTCs with the HDS.
  2. Turn the ignition switch OFF, and then back ON (II).
  3. Check for DTCs with the HDS.

    Is DTC B1843 indicated? 

    YES  - Go to step 4.

    NO  - Intermittent failure, the system is OK at this time. Check for loose or poor connections.

  4. Move the power mirrors in each direction with the power mirrors switch.

    Do the power mirrors move in each direction smoothly? 

    YES  - Go to step 5.

    NO  - Go to step  10.

  5. Turn the ignition switch OFF.
  6. Disconnect power seat control unit connector A (40P).
  7. Disconnect the power mirror control unit connector (24P).
  8. Check for continuity between power seat control unit connector A (40P) terminal No. 39 and the power mirror control unit connector (24P) terminal No. 13.
    Fig 1: Checking Continuity Between Power Seat Control Unit Connector A (40P) Terminal No. 39 And (24P)
    G05447747Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Go to step 9.

    NO  - Repair open in the wire.

  9. Check for continuity between power seat control unit connector A (40P) terminal No. 39 and body ground.
    Fig 2: Checking Continuity Between Power Seat Control Unit Connector A (40P) Terminal No. 39 And Body Ground
    G05447748Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Repair short in the wire.

    NO  - Substitute a known-good power mirror control unit and recheck. If DTC B1843 is still indicated, replace the power seat control unit.

  10. Turn the ignition switch OFF.
  11. Disconnect the power mirror control unit connector (24P).
  12. Turn the ignition switch ON (II).
  13. Measure the voltage between the power mirror control unit connector (24P) terminal No. 11 and No. 22 and between terminal No. 24 and No. 22.
    Fig 3: Measuring Voltage Between Power Mirror Control Unit Connector (24P) Terminal No. 11 And No. 22
    G05447749Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES  - Replace the power mirror control unit.

    NO  - Repair an open in the wire.

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