B1843

DTC Troubleshooting: B1843

DTC B1843:

UART Communication Error

NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A Troubleshooting - B-CAN System Diagnosis Test Mode A.

1. Clear the DTCs with the HDS.

2. Turn the ignition switch to LOCK (0), and then back to ON (II), or press the engine start/stop button to select the OFF mode and then the ON mode.

3. Operate the power seat with the driving position memory switch.

4. 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.

5. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

6. Disconnect these items:

- Power seat control unit connector A (18P)
- Power seat control unit connector B (40P)
- Power mirror control unit 24P connector

7. Check for continuity between power seat control unit connector B (40P) terminal No. 38 and power mirror control unit 24P connector terminal No. 13.





Is there continuity?

YES -

Go to step 8.

NO -

Repair an open in the UART wire between the power mirror control unit and the power seat control unit.

8. Disconnect the power tilt/telescopic steering control unit connectors.

9. Check for continuity between body ground and power seat control unit connector B (40P) terminal No. 38.





Is there continuity?

YES -

Repair a short to ground in the UART wire.

NO -

Go to step 10.

10. Reconnect the power mirror control unit 24P connector.

11. Measure the voltage between body ground and power mirror control unit 24P connector terminal No. 24.





Is there battery voltage?

YES -

Go to step 12.

NO -

Check No. 15 (10 A) fuse in the under-hood fuse/relay box. If the fuse is OK, repair an open or high resistance in the wire.

12. Check for continuity between body ground and power mirror control unit 24P connector terminal No. 22.





Is there continuity?

YES -

Replace the power mirror control unit Power Mirror Control Unit Input Test/Replacement.

NO -

Repair an open or high resistance in the wire between the power mirror control unit and body ground (G402). If the wire is OK, repair the body ground (G402).