DTC B1843: UART Communication Error
- Clear the DTC with the HDS.
- Turn the ignition switch to LOCK (0), and then back to ON (II).
- Operate the power seat with the driving position memory switch.
- Check for DTCs with the HDS.
Is DTC B1843 indicated?
YES -Go to step 5.
NO -Intermittent failure, the system is OK at this time. Check for loose or poor connections.
- Turn the ignition switch to LOCK (0).
- Disconnect power seat control unit connector B (40P).
- Disconnect the power mirror control unit 24P connector.
- Check for continuity between power seat control unit connector B (40P) terminal No. 23 and power mirror control unit 24P connector terminal No. 24.Fig 1: Checking For Continuity Between Power Seat Control Unit Connector B (40P) Terminal No. 23 & Power Mirror Control Unit 24P Connector Terminal No. 24
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Go to step 9.
NO -Repair an open in the UART wire between the power mirror control unit and power seat control unit.
- Check for continuity between body ground and power seat control connector B (40P) terminal No. 23.Fig 2: Checking For Continuity Between Body Ground And Power Seat Control Connector B (40P) Terminal No. 23
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Repair a short to ground in the UART wire.
NO -Go to step 10.
- Reconnect the power mirror control unit 24P connector.
- Measure the voltage between body ground and power mirror control unit 24P connector terminal No. 13.Fig 3: Measuring Voltage Between Body Ground & Power Mirror Control Unit 24P Connector Terminal No. 13
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there battery voltage?
YES -Go to step 12.
NO -Check No. B16 (10 A) fuse in the under-hoodfuse/relay box. If the fuse is OK, repair an open in or high resistance the wire.
- Turn the ignition switch to ON (II).
- Measure the voltage between body ground and power mirror control unit 24P connector terminal No. 15.Fig 4: Measuring Voltage Between Body Ground And Power Mirror Control Unit 24P Connector Terminal No. 15
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there less than 0.2 V?
YES -Replace the power mirror control unit (see Power Seat Control Unit Input Test/Replacement ).
NO -Repair an open or high resistance in the wire between the power mirror control unit and body ground (G401). If the wire is OK, repair G401.