2021 Subaru WRX BaseFACTORY OEM SERVICE PROCEDURE

DTC B2256: Data Communication Module Communication Open

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

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 (DIAGNOSTICS)>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 code)

    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 AND CABLE CONNECTION  .
    1. Turn the ignition switch to OFF.
    2. Check that the cockpit control module and DCM connector are securely connected.

    Is the check result OK?

    Yes  : Go to  3.

    No  : Connect the connector.

  3. CHECK CONNECTOR AND CABLE  .

    Visually check the connector, terminal or cable body.

    Is the check result OK?

    Yes  : Go to  4.

    No  : Replace the cable.

  4. CHECK DCM  .

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