DTC U0122: Lost Communication With Vehicle Dynamics Control Module

DTC detecting condition: 

No data from VDC CONTROL MODULE is received.

Trouble symptom: 

ABS warning light and VDC warning light illuminate.

1. CHECK CAN COMMUNICATION HARNESS  .

   Perform the basic diagnostic procedure to check for fault in CAN communication harness. Ref. to LAN SYSTEM (DIAGNOSTICS)>Basic Diagnostic Procedure 

   Was the basic diagnostic procedure performed up to step  7?

   Yes: Go to  2

   No: Perform the basic diagnostic procedure. Ref. to LAN SYSTEM (DIAGNOSTICS)>Basic Diagnostic Procedure 

2. CHECK DTC (OTHER THAN U-CODE)  .

   Check the displayed DTC.

   Are DTCs other than U*** displayed?

   Yes: Perform the diagnosis for DTCs other than the displayed U-code.

   No: Go to  3

3. CHECK DTC (CURRENT MALFUNCTION)  .

   Check the displayed DTC.

   Is U0122 a current malfunction?

   Yes: Go to  4

   No: Go to  6

4. CHECK DTC (CURRENT MALFUNCTION)  .
   1. Check CAN communication circuit. Ref. to LAN SYSTEM (DIAGNOSTICS)>CAN Communication Circuit Check 
   2. Read the DTC using Subaru Select Monitor. Ref. to LAN SYSTEM (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC) 

   Is U0122 a current malfunction?

   Yes: Go to  5

   No: Go to  6

5. CHECK DTC  .

   Using the Subaru Select Monitor, read DTC of all the systems. Ref. to LAN SYSTEM (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC) 

   Is U0122 detected in several modules?

   Yes: Replace the VDC CONTROL MODULE. Ref. to VEHICLE DYNAMICS CONTROL (VDC)>VDC Control Module and Hydraulic Control Unit (VDC CONTROL MODULE&H/U)

   No: Replace the module that the DTC has been detected.

6. CHECK HARNESS  .
   1. Shake the harness, and check for poor contact.
   2. Read the DTC using Subaru Select Monitor. Ref. to LAN SYSTEM (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC) 

   Is U0122 a current malfunction?

   Yes: Repair the poor contact of harness, or replace the harness.

   No: Go to  7

7. CHECK CONNECTOR  .

   Check the connector used for high speed CAN for poor contact.

   Is there poor contact of connector?

   Yes: Repair the connector that has poor contact, or replace harness.

   No: It is possible that temporary poor communication occurs. Delete the DTC.