B1142

DTC Troubleshooting: B1142

DTC B1142: Communication Line (UART Line) 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. Open and close the driver's and front passenger's windows by operating the power window master switch.

4. 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.


5. Turn the ignition switch to LOCK (0).

6. Disconnect the door multiplex control unit 37P connector.

7. Disconnect the front passenger's power window switch 37P connector.

8. Check for continuity between the door multiplex control unit 37P connector terminal No. 27 and body ground.

Is there continuity?
YES - Repair a short to ground in the wire.

NO - Go to step 9.






9. Check for continuity between the door multiplex control unit 37P connector terminal No. 27 and the front passenger's power window switch 37P connector terminal No. 29.

Is there continuity?
YES - Go to step 10.

NO - Repair an open in the wire.






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

11. Measure the voltage between the door multiplex control unit 37P connector terminal No. 27 and body ground.

Is there less than 1 V?
YES - Go to the passenger's power window switch input test, and do all the power and ground input tests. Front Passengers Power Window Switch Input Test If the tests prove OK, substitute a known good passenger's power window switch. If the DTC goes away, replace the original passenger's power window switch. If the DTC is still present, replace the power window master switch.

NO - Repair a short to power in the wire.