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DTC U1233: Lost Communication With RAB Control Module

DTC detecting condition: 

No data is received from RAB Control Module.

Trouble symptom: 

Coordination control of RAB Control Module does not operate normally.

CAUTION: When the keyless access Control Module is replaced, registration of the immobilizer is required. For the relevant procedures, refer to the "REGISTRATION MANUAL FOR IMMOBILIZER".
  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 U1233 a current malfunction?

    Yes: Go to  4.

    No: Go to  6.

  4. CHECK DTC  .
    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)>Diagnostic Trouble Code (DTC) .

    Is U1233 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)>Diagnostic Trouble Code (DTC) .

    Is U1233 detected in several modules?

    Yes: Replace the RAB Control Module. Ref. to Reverse Automatic Braking>REVERSE AUTOMATIC BRAKING CONTROL MODULE .

    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)>Diagnostic Trouble Code (DTC) .

    Is U1233 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. Ref. to LAN SYSTEM (DIAGNOSTICS)>Clear memory .

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