2021 Subaru Outback BaseFACTORY OEM SERVICE PROCEDURE

DTC B2256: Data Communication Module Communication Open

DTC detecting condition: 

  • Detected when a DCM that operates properly is not connected via USB.
  • Detected when the DCM is not connected via USB.

Trouble symptom: 

DCM linkage function cannot be used.

CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to COCKPIT CONTROL (DIAGNOSTICS)>General Description>CAUTION .
  1. CHECK DTC  .
    1. Using the Subaru Select Monitor, perform the clear memory of [Cockpit Control]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
    2. Turn the ignition switch OFF → ON.
    3. Read the DTC of [Cockpit Control] using the Subaru Select Monitor. Ref. to Cockpit Control (Diagnostics)>Diagnostic Trouble Code (DTC) .

    Is DTC B2256 displayed? (Current malfunction)

    Yes:  Go to  2 .

    No:  Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

    NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
  2. CHECK CONNECTOR  .

    Check the harness between the cockpit control module connector and DCM.

    Is the check result OK?

    Yes:  Go to  3 .

    No:  Repair the harness or replace the components.

  3. CHECK DCM  .

    Perform the inspection according to the diagnosis for telematics system. Ref. to TELEMATICS SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .

    Is the check result OK?

    Yes:  Replace the cockpit control module. Ref. to ENTERTAINMENT & MONITORING>COCKPIT DISPLAY .

    No:  Replace the DCM. Ref. to ENTERTAINMENT & MONITORING>DATA COMMUNICATION MODULE .

Chapter Navigation
Return to Chapter: Diagnostic Procedure With Diagnostic Trouble Code (DTC)
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.