DTC : B1843

DTC B1843  : LOCAL communication error

DTC (Power Seat Control Unit)

NOTE:  If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Go to: Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks .

1. Problem verification

   - 1. Clear the DTCs with the HDS.

   Clear DTCs

   - 2. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

   - 3. Operate the power seat and power mirror with the driving position memory switch.

   - 4. Check for DTCs with the HDS.

   DTC Description	DTC
   B1843 LOCAL communication error

   Is DTC B1843 indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for loose or poor connections.

2. Open wire check (UART (DPMS) line)

   - 1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Disconnect the following connectors.

   Power seat control unit connector A (20P)

   Power mirror control unit 24P connector

   - 3. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode Power seat control unit connector A (20P): disconnected Power mirror control unit 24P connector: disconnected
   Test point 1	Power seat control unit connector A (20P) No. 18
   Test point 2	Power mirror control unit 24P connector No. 24

   Is there continuity?

   YES 

   The UART (DPMS) wire is not open. Go to step 3.

   NO 

   Repair an open or high resistance in the wire.

3. Shorted wire check (UART (DPMS) line to power)

   - 1. Turn the vehicle to the ON mode.

   - 2. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle ON mode Power seat control unit connector A (20P): disconnected Power mirror control unit 24P connector: disconnected
   Test point 1	Power seat control unit connector A (20P) No. 18
   Test point 2	Body ground

   Is there less than 0.2 V?

   YES 

   The UART (DPMS) wire is not shorted to power. Go to step 4.

   NO 

   Repair a short to power in the wire.

4. Shorted wire check (UART (DPMS) line)

   - 1. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode Power seat control unit connector A (20P): disconnected Power mirror control unit 24P connector: disconnected
   Test point 1	Power seat control unit connector A (20P) No. 18
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short to ground in the wire.

   NO 

   The UART (DPMS) wire is OK. Go to step 5.

5. Control unit check (input test)

   - 1. Do the each control unit input test.

   • Power Mirror Control Unit

   Is the control unit input test OK?

   YES 

   Go to step 6.

   NO 

   Repair the malfunction circuit, then recheck the system.

6. Power mirror control unit check (substitution)

   - 1. Substitute a known good power mirror control unit.

   - 2. Clear the DTCs with the HDS.

   Clear DTCs

   - 3. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

   - 4. Operate the power seat and power mirror with the driving position memory switch.

   - 5. Check for DTCs with the HDS.

   DTC Description	DTC
   B1843 LOCAL Communication Error

   Is DTC B1843 indicated?

   YES 

   Replace the Power Seat Control Unit - Removal and Installation .

   NO 

   Replace the original Power Mirror Control Unit - Removal and Installation .