DTC U0300-51: Internal Control Module Software Incompatibility Not Programmed [09/2020 - 10/2022]: Procedure

2025 Toyota Highlander Hybrid XLESECTION Procedure
  1. CONFIRM MODEL 
    1. Choose the model to be inspected.

      Result

      Result Proceed to
      for HV Model A
      for Gasoline Model B

    Result: 

    See step  5

    Result: 

    See step  2

  2. CHECK FOR DTCs 
    1. Using the GTS, check for hybrid control system DTCs.

      Powertrain > Hybrid Control > Trouble Codes 

      Result

      Result Proceed to
      Hybrid control system DTCs are not output A
      Hybrid control system DTCs are output B

    Result: 

    GO TO HYBRID CONTROL SYSTEM 

    for AWD: Refer to HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - 11/2023]

    for 2WD: Refer to HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - 11/2023]

    Result: 

    See step  3

  3. CHECK FOR DTCs (HEALTH CHECK) 
    1. Check DTCs.
    2. Turn the ignition switch off.

      OK

      DTCs indicating a vehicle information mismatch with the hybrid vehicle control ECU are not output by any ECU other than the forward recognition camera.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE HYBRID VEHICLE CONTROL ECU. Refer to  REMOVAL [12/2019 - 10/2022] 

    Result: 

    OK 

    See step  4

  4. READ VALUE USING GTS 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Pre-Collision System > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Vehicle Information (Conv/HV/EV) Vehicle information (Conv/HV/EV) Unknown / Conv / HV/EV Unknown: Vehicle information not confirmed
      Conv: Conventional
      HV/EV: Hybrid vehicle
      -
      Vehicle Information (Transmission Type) Vehicle information (transmission type) MT, AT, CVT, MMT, SMT, HV/EV - AT or Unknown Displays the type of transmission -

      Body Electrical > Pre-Collision System > Data List 

      Tester Display
      Vehicle Information (Conv/HV/EV)
      Vehicle Information (Transmission Type)

      HINT: 

      • If the vehicle information stored in the forward recognition camera is different than the actual vehicle specifications, the vehicle information stored in the forward recognition camera may be incorrect. Check for DTCs and replace the forward recognition camera if necessary.
      • If the vehicle information stored in the forward recognition camera matches the actual vehicle specifications, the installed hybrid vehicle control ECU is incompatible. Replace the hybrid vehicle control ECU with a correct one.

      Result

      Result Proceed to
      Vehicle information stored in forward recognition camera and actual vehicle specifications do not match A
      "Unknown" is displayed
      Vehicle information stored in forward recognition camera and actual vehicle specifications match B

    Result: 

    REPLACE FORWARD RECOGNITION CAMERA. Refer to  REMOVAL [09/2020 - 11/2023] 

    Result: 

    REPLACE HYBRID VEHICLE CONTROL ECU. Refer to  REMOVAL [12/2019 - 10/2022] 

  5. CHECK FOR DTCs 
    1. Using the GTS, check for SFI system DTCs.

      Powertrain > Engine > Trouble Codes 

      Result

      Result Proceed to
      SFI system DTCs are not output A
      SFI system DTCs are output B

    Result: 

    GO TO SFI SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - 10/2022] 

    Result: 

    See step  6

  6. CHECK FOR DTCs (HEALTH CHECK) 
    1. Check DTCs.
    2. Turn the ignition switch off.

      OK

      DTCs indicating a vehicle information mismatch with the ECM are not output by any ECU other than the forward recognition camera.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE ECM. Refer to  REMOVAL [09/2020 - 10/2022] 

    Result: 

    OK 

    See step  7

  7. READ VALUE USING GTS 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Pre-Collision System > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Vehicle Information (Conv/HV/EV) Vehicle information (Conv/HV/EV) Unknown / Conv / HV/EV Unknown: Vehicle information not confirmed
      Conv: Conventional
      HV/EV: Hybrid vehicle
      -
      Vehicle Information (Transmission Type) Vehicle information (transmission type) MT, AT, CVT, MMT, SMT, HV/EV - AT or Unknown Displays the type of transmission -

      Body Electrical > Pre-Collision System > Data List 

      Tester Display
      Vehicle Information (Conv/HV/EV)
      Vehicle Information (Transmission Type)

      HINT: 

      • If the vehicle information stored in the forward recognition camera is different than the actual vehicle specifications, the vehicle information stored in the forward recognition camera may be incorrect. Check for DTCs and replace the forward recognition camera if necessary.
      • If the vehicle information stored in the forward recognition camera matches the actual vehicle specifications, the installed ECM is incompatible. Replace the ECM with a correct one.

      Result

      Result Proceed to
      Vehicle information stored in forward recognition camera and actual vehicle specifications do not match A
      "Unknown" is displayed
      Vehicle information stored in forward recognition camera and actual vehicle specifications match B

    Result: 

    REPLACE FORWARD RECOGNITION CAMERA. Refer to  REMOVAL [09/2020 - 11/2023] 

    Result: 

    REPLACE ECM. Refer to  REMOVAL [09/2020 - 10/2022] 

RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.