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Home >> Lexus >> 2009 >> ES 350 >> Repair and Diagnosis (Single Page) >> Brakes >> Traction Control >> Vehicle Stability Control (VSC) System (Diagnostic Codes & Symptom Tests) >> Vehicle Stability Control System >> DTC U0073/94: Control Module Communication Bus OFF; DTC U0100/65: Lost Communication with ECM / PCM; DTC U0123/62: Lost Communication with Yaw Rate Sensor Module; DTC U0124/95: Lost Communication with Lateral Acceleration Sensor Module; DTC U0126/63: Lost Communication with Steering Angle Sensor Module >> Procedure

DTC U0073/94: Control Module Communication Bus OFF; DTC U0100/65: Lost Communication with ECM / PCM; DTC U0123/62: Lost Communication with Yaw Rate Sensor Module; DTC U0124/95: Lost Communication with Lateral Acceleration Sensor Module; DTC U0126/63: Lost Communication with Steering Angle Sensor Module: Procedure

  1. CHECK HARNESS AND CONNECTOR (MOMENTARY INTERRUPTION) 
    1. Using Techstream, check for any momentary interruption in the wire harness and connector corresponding to a DTC . Refer to CHECK FOR INTERMITTENT PROBLEMS .
      ABS / VSC / TRAC:

      Tester Display Measurement Item/Range Normal Condition
      EFI Communication Open EFI communication open detection / ERROR or NORMAL ERROR: Momentary interruption
      NORMAL: Normal
      Steering Open Steering sensor open detection / ERROR or NORMAL ERROR: Momentary interruption
      NORMAL: Normal
      Yaw Rate Open Yaw rate sensor open detection / ERROR or NORMAL ERROR: Momentary interruption
      NORMAL: Normal

      Result

      Condition Proceed to
      There is a constant open circuit A
      There are no momentary interruptions B
      There are momentary interruptions C

      HINT: 

      Perform the above inspection before removing the sensor and connector.

    C → See step   /> 

    B → See step   /> 

    A: Go to next step 

  2. CHECK IF EACH SENSOR AND ECM CONNECTOR IS SECURELY CONNECTED 
    1. Turn the engine switch off.
    2. Check if each sensor or ECM connector is securely connected.

      OK

      The connector should be securely connected.

    NG → CONNECT CONNECTOR TO EACH SENSOR OR ECM CORRECTLY 

    OK: Go to next step 

  3. RECONFIRM DTC 
    1. Turn the engine switch off.
    2. Record the output DTCs (for ABS, VSC, and CAN communication).

      HINT: 

      If the CAN communication system DTC and the relevant sensor DTCs are output simultaneously, troubleshoot the relevant sensor DTCs (for ABS and VSC) after the CAN communication system returns to normal.

      Result

      Condition Proceed to
      DTC (CAN communication system DTC) is output A
      DTC (ABS and/or VSC DTC) is output B
      DTC is not output C

    C → CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) 

    B → See step   /> 

    A → INSPECT CAN COMMUNICATION SYSTEM 

  4. REPAIR OR REPLACE HARNESS OR CONNECTOR 
    1. Turn the engine switch off.
    2. Repair or replace the harness or connector.
    3. Check for any momentary interruption between the skid control ECU and each sensor or ECM . Refer to CHECK FOR INTERMITTENT PROBLEMS .
    4. Check that there is no momentary interruption.

    NEXT: Go to next step 

  5. RECONFIRM DTC 
    1. Turn the engine switch off.
    2. Clear the DTC. Refer to DTC CHECK / CLEAR .
    3. Start the engine.
    4. Drive the vehicle and turn the steering wheel to the right and left at a speed of 15 km/h (9 mph) or more.
    5. Check that no CAN communication system DTC is output.
    6. If ABS and VSC DTCs are output, record them.

      Result

      Condition Proceed to
      DTC output for the CAN communication system A
      No DTC is output (ABS and/or VSC DTC is output) B
      No DTC is output (No ABS and/or VSC DTC is output) C

      HINT: 

      The CAN communication system must be normal when repairing each sensor DTC (for ABS and VSC).

    C → END 

    B → See step   /> 

    A → INSPECT CAN COMMUNICATION SYSTEM 

  6. REPAIR CIRCUIT INDICATED BY OUTPUT DTC. Refer to  DIAGNOSTIC TROUBLE CODE CHART