DTC B1142: Door Multiplex Control Unit Lost Communication with Front Passenger's Power Window Switch (UART line open)

NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A (see TROUBLESHOOTING - B-CAN SYSTEM DIAGNOSIS TEST MODE A ).

Clear the DTCs with the HDS.
Turn the ignition switch OFF, and then back ON (II).
Open and close the front passenger's power window by using the power window master switch manually.
Open and close the front passenger's power window by using the front passenger's power window switch manually.
Check for DTCs with the HDS.
Is DTC B1142 indicated?

YES -Go to step 6.

NO -The system is OK at this time. Check for loose or poor connections at the passenger's power window switch connector.
Turn the ignition switch OFF.
Disconnect the door multiplex control unit connectors and front passenger's power window switch connector.
Check for continuity between door multiplex control unit connector B (14P) No. 4 terminal and front passenger's power window switch 14P connector No. 4 terminals.

Fig 1: Checking Continuity Between Door Multiplex Control Unit No. 4 Terminal And Front Passenger's Power Window Switch No. 4 Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Substitute a known-good front passenger's power window switch, and recheck. If DTC is gone, the original front passenger's power window switch is faulty; replace it. If the DTC B1142 is still indicated, replace the door multiplex control unit.

NO -Repair an open in the wire.