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).

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).

6. Disconnect the power seat control unit connectors and power mirror control unit connector (24P).

7. Check for continuity between power seat control unit connector B (40P) terminal No. 23 and power mirror control unit 24P connector terminal No. 24.





Is there continuity?

YES -

Go to step 8.

NO -

Repair an open in the UART wire between the power mirror control unit 24P connector and power seat control unit connector B (40P).

8. Check for continuity between body ground and power seat control unit connector B (40P) terminal No. 23.





Is there continuity?

YES -

Repair a short to ground in the UART wire.

NO -

Go to step 9.

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

10. Measure the voltage between body ground and power mirror control unit 24P connector terminal No. 13.





Is there battery voltage?

YES -

Go to step 11.

NO -

Check No. A15 (10 A) fuse in the under-hood fuse/relay box. If the fuse is OK, repair an open or high resistance in the wire.

11. Turn the ignition switch to ON (II).

12. Measure the voltage between body ground and power mirror control unit 24P connector terminal No. 15.





Is there 0.2 V or more?

YES -

Replace the power mirror control unit Service and Repair.

NO -

Repair an open or high resistance in the wire between the power mirror control unit and G401. If the wire is OK, repair G401.