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DTC U023A-87: Lost Communication with Image Processing Module "A" Missing Message [08/2021 - ]: Procedure

WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2024 Lexus ES 350, 2024 Lexus ES 300h, 2024 Lexus ES 250, 2023 Lexus ES 350, and 2023 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.
  1. CONFIRM MODEL 
    1. Choose the model to be inspected.

      Result

      Result Proceed to
      For HV Model A
      For Gasoline Model B

    Result: 

    B 

    See step  5

    Result: 

    A 

    See step  2

  2. CHECK FOR DTCs (ABS/VSC/TRAC) 
    1. Using the Techstream, check for electronically controlled brake system DTCs.

      Chassis > ABS/VSC/TRAC > Trouble Codes 

      HINT: 

      If DTC U023A-87 and electronically controlled brake system DTCs are output, perform troubleshooting for the electronically controlled brake system first.

      Result

      Result Proceed to
      Electronically controlled brake system DTCs are not output A
      Electronically controlled brake system DTCs are output B

    Result: 

    B 

    GO TO ELECTRONICALLY CONTROLLED BRAKE SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [06/2018 - ] 

    Result: 

    A 

    See step  3

  3. PERFORM TEST MODE (ELECTRONICALLY CONTROLLED BRAKE SYSTEM) 

    HINT: 

    When entering Test Mode, the skid control ECU (brake booster with master cylinder assembly) communicates with the forward recognition camera to judge whether the vehicle is equipped with the pre-collision system. Therefore, do not exit Test Mode within 5 seconds of entering Test Mode.

    1. Procedure to enter Test Mode
      1. Turn the ignition switch off.
      2. Check that the steering wheel is centered.
      3. Check that the shift lever is in P.
      4. Connect the Techstream to the DLC3.
      5. Turn the ignition switch ON.
      6. Turn the Techstream on.
      7. Switch the skid control ECU (brake booster with master cylinder assembly) to Test Mode using the Techstream. Enter the following menus: Chassis / ABS/VSC/TRAC / Utility / Signal Check.

        Chassis > ABS/VSC/TRAC > Utility 

        Tester Display
        Signal Check

        HINT: 

        Do not exit Test Mode within 5 seconds of entering Test Mode. If Test Mode is exited within 5 seconds of entering Test Mode, DTC U023A-87 may be stored. If DTC U023A-87 is output after exiting Test Mode, enter Test Mode again, wait at least 5 seconds, then recheck for DTCs.

    2. Confirm the system has entered Test Mode.
      1. Confirm that the ABS warning light, brake system warning light (yellow indicator) and slip indicator light indicate the Test Mode pattern (blinking at 0.25 second intervals).

        HINT: 

        • When in Test Mode, "Traction Control Turned Off" is displayed on the multi-information display.
        • When entering Test Mode, if the parking brake is engaged, the parking brake indicator light (red) will illuminate, and if the parking brake is not engaged, the parking brake indicator light (red) will blink in the Test Mode pattern (blinking at 0.25 second intervals).
    3. End of Test Mode
      1. Turn the ignition switch off.
      2. Disconnect the Techstream.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  4

  4. CHECK FOR DTCs 
    1. Clear the DTCs.

      Body Electrical > Pre-Collision System > Clear DTCs 

    2. Make sure that the DTC detection conditions are met.

      HINT: 

      If the detection conditions are not met, the system cannot detect the malfunction.

    3. Check for DTCs.

      Body Electrical > Pre-Collision System > Trouble Codes 

      Result

      Result Proceed to
      DTC U023A-87 is not output A
      DTC U023A-87 is output B

    Result: 

    A 

    END 

    Result: 

    B 

    REPLACE FORWARD RECOGNITION CAMERA. Refer to  REMOVAL [08/2021 - ] 

  5. CHECK FOR DTCs (Brake/EPB) 
    1. Using the Techstream, check for electronically controlled brake system DTCs.

      Chassis > Brake/EPB > Trouble Codes 

      HINT: 

      If DTC U023A-87 and electronically controlled brake system DTCs are output, perform troubleshooting for the electronically controlled brake system first.

      Result

      Result Proceed to
      Electronically controlled brake system DTCs are not output A
      Electronically controlled brake system DTCs are output B

    Result: 

    B 

    GO TO ELECTRONICALLY CONTROLLED BRAKE SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [06/2018 - ] 

    Result: 

    A 

    See step  6

  6. PERFORM TEST MODE (ELECTRONICALLY CONTROLLED BRAKE SYSTEM) 

    HINT: 

    When entering Test Mode, the skid control ECU (brake actuator assembly) communicates with the forward recognition camera to judge whether the vehicle is equipped with the pre-collision system. Therefore, do not exit Test Mode within 5 seconds of entering Test Mode.

    1. Procedure to enter Test Mode
      1. Turn the ignition switch off.
      2. Check that the steering wheel is centered.
      3. Check that the shift lever is in P.
      4. Connect the Techstream to the DLC3.
      5. Turn the ignition switch to ON.
      6. Turn the Techstream on.
      7. Switch the skid control ECU (brake actuator assembly) to Test Mode using the Techstream. Enter the following menus: Chassis / Brake/EPB / Utility / Signal Check.

        Chassis > Brake/EPB > Utility 

        Tester Display
        Signal Check

        HINT: 

        Do not exit Test Mode within 5 seconds of entering Test Mode. If Test Mode is exited within 5 seconds of entering Test Mode, DTC U023A-87 may be stored. If DTC U023A-87 is output after exiting Test Mode, enter Test Mode again, wait at least 5 seconds, then recheck for DTCs.

    2. Confirm the system has entered Test Mode.
      1. Confirm that the ABS warning light, brake system warning light (yellow indicator) and slip indicator light indicate the Test Mode pattern (blinking at 0.25 second intervals).

        HINT: 

        • When in Test Mode, "Traction Control Turned Off" is displayed on the multi-information display.
        • When entering Test Mode, if the parking brake is engaged, the parking brake indicator light (red) will illuminate, and if the parking brake is not engaged, the parking brake indicator light (red) will blink in the Test Mode pattern (blinking at 0.25 second intervals).
    3. End of Test Mode
      1. Turn the ignition switch off.
      2. Disconnect the Techstream.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  7

  7. CHECK FOR DTCs 
    1. Clear the DTCs.

      Body Electrical > Pre-Collision System > Clear DTCs 

    2. Make sure that the DTC detection conditions are met.

      HINT: 

      If the detection conditions are not met, the system cannot detect the malfunction.

    3. Check for DTCs.

      Body Electrical > Pre-Collision System > Trouble Codes 

      Result

      Result Proceed to
      DTC U023A-87 is not output A
      DTC U023A-87 is output B

    Result: 

    A 

    END 

    Result: 

    B 

    REPLACE FORWARD RECOGNITION CAMERA. Refer to  REMOVAL [08/2021 - ] 

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