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 to LOCK (0) and then back to ON (II).
Open and close the driver's and front passenger's windows by operating the power window master switch.
Check for DTCs with the HDS.
Is DTC B1142 indicated?

YES -Go to step 5.

NO -Intermittent failure, the system is OK at this time.
Turn the ignition switch to LOCK (0).
Disconnect the power window master switch 37P connector.
Disconnect the front passenger's power window switch 37P connector and the moonroof control unit/motor connector 10P connector (if equipped).
Check for continuity between power window master switch 37P connector terminal No. 27 and body ground.

Fig 1: Checking Continuity Between Power Window Master Switch 37P Connector Terminal No. 27 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to ground in the wire.

NO -Go to step 9.
Check for continuity between power window master switch 37P connector terminal No. 27 and front passenger's power window switch 37P connector terminal No. 29.

Fig 2: Checking Continuity Between Power Window Master Switch 37P Connector Terminal No. 27 And Front Passenger's Power Window Switch 37P Connector Terminal No. 29
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 10.

NO -Repair an open in the UART wire.
Turn the ignition switch to ON (II).
Measure the voltage between power window master switch 37P connector terminal No. 27 and body ground.

Fig 3: Measuring Voltage Between Power Window Master Switch 37P Connector Terminal No. 27 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there less than 0.2 V?

YES -Do the front passenger's power window switch input test, and do all power and ground input tests (see step 5 under Front Passenger's Power Window Switch Input Test ). If the tests prove OK, substitute a known good front passenger's power window switch. If the DTC goes away, replace the original front passenger's power window switch (see FRONT PASSENGER'S POWER WINDOW SWITCH REPLACEMENT ). If the DTC is still present, replace the power window master switch (see POWER WINDOW MASTER SWITCH REPLACEMENT ).

NO -Repair a short to power in the wire.