DTC U128D: Power Seat Control Unit Lost Communication With Gauge Control Module (VSP/NE Frame) (Power Seat Control Unit)

DTC (Power Seat 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. Wait for at least 6 seconds.

   - 4. Check for DTCs with the HDS.

   DTC Description	DTC
   U128D Power Seat Control Unit Lost Communication With Gauge Control Module (VSP/NE Frame)

   Is DTC U128D indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for loose or poor connections.

2. Determine possible failure area (gauge control module power and ground, B-CAN line)

   -1. Select GAUGES from the BODY ELECTRICAL SYSTEM SELECT menu, and then select DATA LIST.

   Does the DATA LIST appear?

   YES 

   Go to step 5. Refer to:  5

   NO 

   Go to step 3.

3. Fuse check

   -1. Check the following fuse.

   Fuse	No. A29 (10 A)
   Location	Under-hood fuse/relay box

   Is the fuse OK?

   YES 

   Go to step 4.

   NO 

   Replace the fuse. If the fuse blows again, repair a short to ground in the No. A29 (10 A) fuse circuit.

4. Open wire check (+B BACK UP line)

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

   - 2. Disconnect the following connector.

   Gauge control module 32P connector

   - 3. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode Gauge control module 32P connector: disconnected
   Test point 1	Gauge control module 32P connector No. 1 - Refer to: Gauge Control Module Input Test (2015-17) or Gauge Control Module Input Test (2018-19)
   Test point 2	Body ground

   Is there battery voltage?

   YES 

   Repair an open or high resistance in the ground wire or poor ground (G305).

   NO 

   Repair an open or high resistance in the wire.

5. Open wire check (B-CAN_H line)

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

   - 2. Disconnect the following connectors.

   Power seat control unit connector A (20P)

   Gauge control module 32P connector

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

   Test condition	Vehicle OFF (LOCK) mode Power seat control unit connector A (20P): disconnected Gauge control module 32P connector: disconnected
   Test point 1	Power seat control unit connector A (20P) No. 16 - Refer to: Driving Position Memory System (Door Multiplex Control Unit, Power Mirror Control Unit, And Power Seat Control Unit) Input Test (2015-17) or Driving Position Memory System (Door Multiplex Control Unit, Power Mirror Control Unit, and Power Seat Control Unit) Input Test (2018-19)
   Test point 2	Gauge control module 32P connector No. 25 - Refer to: Gauge Control Module Input Test (2015-17) or Gauge Control Module Input Test (2018-19)

   Is there continuity?

   YES 

   The B-CAN_H wire is OK. Go to step 6.

   NO 

   An open or poor connection in the B-CAN_H wire between the power seat control unit and the gauge control module.

6. Open wire check (B-CAN_L line)

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

   Test condition	Vehicle OFF (LOCK) mode Power seat control unit connector A (20P): disconnected Gauge control module 32P connector: disconnected
   Test point 1	Power seat control unit connector A (20P) No. 17 - Refer to: Driving Position Memory System (Door Multiplex Control Unit, Power Mirror Control Unit, And Power Seat Control Unit) Input Test (2015-17) or Driving Position Memory System (Door Multiplex Control Unit, Power Mirror Control Unit, and Power Seat Control Unit) Input Test (2018-19)
   Test point 2	Gauge control module 32P connector No. 26 - Refer to: Gauge Control Module Input Test (2015-17) or Gauge Control Module Input Test (2018-19)

   Is there continuity?

   YES 

   The B-CAN_L wire is OK. Replace the gauge control module .

   NO 

   An open or poor connection in the B-CAN_L wire between the power seat control unit and the gauge control module.