DTC U0128: Gauge Control Module Lost Communication With Electric Parking Brake Control Unit (V6, Gauge Control Module without CAN gateway)

DTC (Gauge Control Module)

NOTE:  Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information - Refer to: Network Communications System Description (2015-17) or Network Communications System Description (With SH-AWD) (2015-17) or Network Communications System Description (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
   U0128 Gauge Control Module Lost Communication With Electric Parking Brake Control Unit

   Is DTC U0128 indicated?

   YES 

   Go to step 2.

   NO 

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

2. Fuse check

   -1. Check the following fuse.

   Fuse	No. B7 (7.5 A)
   Location	Under-dash fuse/relay box

   Is the fuse OK?

   YES 

   Go to step 3.

   NO 

   Replace the fuse. If the fuse blows again, repair a short to ground in the No. B7 (7.5 A) fuse circuit.

3. Open wire check (IG1 OPTION line)

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

   - 2. Disconnect the following connector.

   Electric parking brake control unit 30P connector

   - 3. Turn the vehicle to the ON mode.

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

   Test condition	Vehicle ON mode Electric parking brake control unit 30P connector: disconnected
   Test point 1	Electric parking brake control unit 30P connector No. 24 - Refer to: Electric Parking Brake Control Unit Connector for Inputs and Outputs (2015-17) or Electric Parking Brake Control Unit Connector for Inputs and Outputs (2018-19)
   Test point 2	Body ground

   Is there battery voltage?

   YES 

   The IG1 OPTION wire is OK. Go to step 4.

   NO 

   Repair an open or high resistance in the wire.

4. Open wire check (GND lines)

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

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

   Test condition	Vehicle OFF (LOCK) mode Electric parking brake control unit 30P connector: disconnected
   Test point 1	Electric parking brake control unit 30P connector No. 5 - Refer to: Electric Parking Brake Control Unit Connector for Inputs and Outputs (2015-17) or Electric Parking Brake Control Unit Connector for Inputs and Outputs (2018-19)
   Test point 2	Body ground

   Test point 1	Electric parking brake control unit 30P connector No. 7 - Refer to: Electric Parking Brake Control Unit Connector for Inputs and Outputs (2015-17) or Electric Parking Brake Control Unit Connector for Inputs and Outputs (2018-19)
   Test point 2	Body ground

   Is there continuity?

   YES 

   The GND wires are OK. Go to step 5.

   NO 

   Repair an open or high resistance in the ground wire or poor ground (G403).

5. Open wire check (F-CAN A lines)

   -1. Connect terminals A and B with a jumper wire.

   Terminal A	Electric parking brake control unit 30P connector No. 29 - Refer to: Electric Parking Brake Control Unit Connector for Inputs and Outputs (2015-17) or Electric Parking Brake Control Unit Connector for Inputs and Outputs (2018-19)
   Terminal B	Electric parking brake control unit 30P connector No. 30 - Refer to: Electric Parking Brake Control Unit Connector for Inputs and Outputs (2015-17) or Electric Parking Brake Control Unit Connector for Inputs and Outputs (2018-19)

   - 2. Disconnect the following connector.

   Gauge control module 32P connector

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

   Test condition	Vehicle OFF (LOCK) mode Electric parking brake control unit 30P connector: disconnected Gauge control module 32P connector: disconnected
   Test point 1	Gauge control module 32P connector No. 27 - Refer to: Gauge Control Module Input Test (2015-17), or Gauge Control Module Input Test (2018-19)
   Test point 2	Gauge control module 32P connector No. 28 - Refer to: Gauge Control Module Input Test (2015-17), or Gauge Control Module Input Test (2018-19)

   Is there continuity?

   YES 

   The F-CAN A wires are OK. Replace the gauge control module .

   NO 

   An open or poor connection in the F-CAN A wires between the electric parking brake control unit and the gauge control module.