B1843

DTC Troubleshooting: B1843

DTC B1843:

Power Seat Control Unit Lost Communication With Power Mirror Control Unit (UART line)

'08-10 Touring models

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 DTC 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.�

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 A (40P) terminal No. 39 and power mirror control unit connector (24P) terminal No. 13.





Is there continuity?

YES -

Go to step 8.

NO -

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

8. Check for continuity between power seat control unit connector A (40P) terminal No. 39 and body ground.





Is there continuity?

YES -

Repair a short to ground in the wire.�

NO -

Go to step 9.

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





Is there battery voltage?

YES -

Go to step 10.

NO -

Check No. 7 (7.5 A) fuse in the driver's under-dash fuse/relay box. If the fuse is OK, repair an open in the WHT/RED wire.�

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





Is there continuity?

YES -

Repair an open in the wire between the power mirror control unit and G601. If the wire is OK, repair G601.�

NO -

Replace the power mirror control unit.�