DTC B1142: Door Multiplex Control Unit Lost Communication With Front Passenger's Power Window Switch (UART Line Open)

DTC (Door Multiplex Control Unit)

NOTE:  If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Refer to: Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks (2015-17), or Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks (2018-19) .

1. Problem verification

   -1. Clear the DTCs with the HDS.

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

   - 3. Open and close all power windows by operating the power window master switch.

   - 4. Check for DTCs with the HDS.

   DTC Description	DTC
   B1142 Door Multiplex Control Unit Lost Communication With Front Passenger's Power Window Switch (UART Line Open)

   Is DTC B1142 indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time.

2. Open wire check (LIN (P/W) line) 1

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

   - 2. Disconnect the following connectors.

   Power window master switch 37P connector

   Front passenger's power window switch 37P connector

   Left rear power window switch 14P connector

   Right rear power window switch 14P connector

   Moonroof control unit/motor 14P connector

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

   Test condition	Vehicle OFF (LOCK) mode Power window master switch 37P connector: disconnected Front passenger's power window switch 37P connector: disconnected Left rear power window switch 14P connector: disconnected Right rear power window switch 14P connector: disconnected Moonroof control unit/motor 14P connector: disconnected
   Test point 1	Power window master switch 37P connector No. 36
   Test point 2	Front passenger's power window switch 37P connector No. 34 - Refer to: Front Passenger's Power Window Switch Input Test

   Is there continuity?

   YES 

   The LIN (P/W) wire is not open between power window master switch and front passenger's power window switch. Go to step 3.

   NO 

   Repair an open or high resistance in the wire.

3. Open wire check (LIN (P/W) line) 2

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

   Test condition	Vehicle OFF (LOCK) mode Power window master switch 37P connector: disconnected Front passenger's power window switch 37P connector: disconnected Left rear power window switch 14P connector: disconnected Right rear power window switch 14P connector: disconnected Moonroof control unit/motor 14P connector: disconnected
   Test point 1	Power window master switch 37P connector No. 36
   Test point 2	Left rear power window switch 14P connector No. 9 - Refer to: Left Rear Power Window Switch Input Test

   Is there continuity?

   YES 

   The LIN (P/W) wire is not open between power window master switch and left rear power window switch. Go to step 4.

   NO 

   Repair an open or high resistance in the wire.

4. Open wire check (LIN (P/W) line) 3

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

   Test condition	Vehicle OFF (LOCK) mode Power window master switch 37P connector: disconnected Front passenger's power window switch 37P connector: disconnected Left rear power window switch 14P connector: disconnected Right rear power window switch 14P connector: disconnected Moonroof control unit/motor 14P connector: disconnected
   Test point 1	Power window master switch 37P connector No. 36
   Test point 2	Right rear power window switch 14P connector No. 9 - Refer to: Right Rear Power Window Switch Input Test

   Is there continuity?

   YES 

   The LIN (P/W) wire is not open between power window master switch and right rear power window switch. Go to step 5.

   NO 

   Repair an open or high resistance in the wire.

5. Open wire check (LIN (P/W) line) 4

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

   Test condition	Vehicle OFF (LOCK) mode Power window master switch 37P connector: disconnected Front passenger's power window switch 37P connector: disconnected Left rear power window switch 14P connector: disconnected Right rear power window switch 14P connector: disconnected Moonroof control unit/motor 14P connector: disconnected
   Test point 1	Power window master switch 37P connector No. 36
   Test point 2	Moonroof control unit/motor 14P connector No. 12 - Refer to: Moonroof Motor-Control Unit Input Test (2015-17) or Moonroof Motor-Control Unit Input Test (2018-19)

   Is there continuity?

   YES 

   The LIN (P/W) wire is not open between power window master switch and moonroof control unit/motor. Go to step 6.

   NO 

   Repair an open or high resistance in the wire.

6. Shorted wire check (LIN (P/W) line)

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

   Test condition	Vehicle OFF (LOCK) mode Power window master switch 37P connector: disconnected Front passenger's power window switch 37P connector: disconnected Left rear power window switch 14P connector: disconnected Right rear power window switch 14P connector: disconnected Moonroof control unit/motor 14P connector: disconnected
   Test point 1	Power window master switch 37P connector No. 36
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short to ground in the wire.

   NO 

   The LIN (P/W) wire is not shorted to ground. Go to step 7.

7. Shorted wire check (LIN (P/W) 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 window master switch 37P connector: disconnected Front passenger's power window switch 37P connector: disconnected Left rear power window switch 14P connector: disconnected Right rear power window switch 14P connector: disconnected Moonroof control unit/motor 14P connector: disconnected
   Test point 1	Power window master switch 37P connector No. 36
   Test point 2	Body ground

   Is there less than 0.2 V?

   YES 

   The LIN (P/W) wire is OK. Go to the front passenger's power window switch input test - Refer to: Front Passenger's Power Window Switch Input Test and do the power and ground input tests. 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 - Refer to: Front Passenger's Power Window Switch Removal and Installation, . If the DTC is still present, replace the power window master switch .

   NO 

   Repair a short to power in the wire.