DTC U128D: Door Multiplex Control Unit Lost Communication With Gauge Control Module

DTC (Door Multiplex Control Unit)

• 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 Door Multiplex Control Unit Lost Communication With Gauge Control Module

  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 6.

  NO 

  Go to step 3.

• 3. Fuse check:

  1. Check the following fuses.

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

  Is each 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 connector A (32P)

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

  Test condition	Vehicle OFF (LOCK) mode Gauge control module connector A (32P): disconnected
  Test point 1	Gauge control module connector A (32P) No. 1
  Test point 2	Body ground

  Is there battery voltage?

  YES 

  Repair an open or high resistance in the ground wire or poor ground (G502).

  NO 

  Repair an open or high resistance in the wire.

• 5. Open wire check (B-CAN_H lines):

  1. Disconnect the following connector.

  Power window master switch 37P connector Gauge control module connector A (32P)

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

  Test condition	Vehicle OFF (LOCK) mode Power window master switch 37P connector: disconnected Gauge control module connector A (32P): disconnected
  Test point 1	Power window master switch 37P connector No. 28 - Refer to: Power Window Master Switch Input Test(Without Door Multiplex Control Unit)Power Window Master Switch Input Test(With Door Multiplex Control Unit)
  Test point 2	Gauge control module connector A (32P) No. 30

  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 window master switch and the gauge control module.

• 6. Open wire check (B-CAN_L lines):

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

  Test condition	Vehicle OFF (LOCK) mode Power window master switch 37P connector: disconnected Gauge control module connector A (32P): disconnected
  Test point 1	Power window master switch 37P connector No. 30 - Refer to: Power Window Master Switch Input Test(Without Door Multiplex Control Unit)Power Window Master Switch Input Test(With Door Multiplex Control Unit)
  Test point 2	Gauge control module connector A (32P) No. 31

  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 window master switch and the gauge control module.