DTC Troubleshooting: B1142
DTC B1142:
 Communication Line (UART Line) Communication Error
NOTE: Before troubleshooting, check the No. 16 (7.5 A), No. 20 (20 A) and No. 24 (20 A) fuses in the driver's under-dash fuse/relay box.
  1. Clear the DTC with the HDS.
  1. Turn the ignition switch to LOCK (0) and then back to ON (II).
  1. Open and close all power windows by operating the power window master switch.
  1. 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. Check for loose or poor connections.■
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect the door multiplex control unit 37P connector.
  1. Disconnect the sunroof control unit 14P connector.
  1. With all power window AUTO UP/AUTO DOWN function: Disconnect each rear power window switch 14P connector.
  1. Check for continuity between the door multiplex control unit 37P connector No. 27 terminal and sunroof control unit 14P connector No. 11 terminal.
Is there continuity?
YES -
Go to Step 10 .
NO -
An open in the wire.■
  1. Disconnect the front passenger's power window switch 37P connector.
  1. Check for continuity between the door multiplex control unit 37P connector No. 27 terminal and the front passenger's power window switch 37P connector No. 29 terminal.
Is there continuity?
YES -
  • With all power windows AUTO UP/AUTO DOWN function: Go to Step 12 .
  • Without all power windows AUTO UP/AUTO DOWN function: Substitute a known-good power window master switch, then reset the power window control unit and recheck. If the DTC goes away, replace the original power window master switch. If the DTC is still present, replace the passenger's power window switch.■
NO -
An open in the wire.■
  1. Check for continuity between the door multiplex control unit 37P connector No. 27 terminal and the left rear power window switch 14P connector No. 12 terminal.
Is there continuity?
YES -
Go to Step 13 .
NO -
An open in the wire.■
  1. Check for continuity between the door multiplex control unit 37P connector No. 27 terminal and the right rear power window switch 14P connector No. 12 terminal.
Is there continuity?
YES -
Substitute a known-good power window master switch, then reset the power window control unit and recheck. If the DTC goes away, replace the original power window master switch. If the DTC is still present, substitute a known-good passenger's power window switch one at a time and recheck.■
NO -
An open in the wire.■