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DTC U0104-87: Lost Communication with Cruise Control Module Missing Message [01/2023 - ]: Procedure

WARNING: This page is about a different car, the 2024 Lexus RC F and 2023 Lexus RC F. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK FOR DTCs 
    1. Read each DTC and check the diagnosis pattern using the table below.

      Body Electrical > Front Radar Sensor > Trouble Codes 

      Body Electrical > Pre-Collision System > Trouble Codes 

      Chassis > Lane Control > Trouble Codes 

      Body Electrical > Front Recognition Camera (Front Lighting Control) > Trouble Codes 

      Powertrain > Radar Cruise2 > Trouble Codes 

      Pattern DTC output part name
      (Display on Techstream)
      Front Radar Sensor Pre-Collision System Lane Control Forward Recognition Camera (Front Lighting Control) Radar Cruise2
      Pattern 1 U0104-87 U0235-87 U0235-87 U0235-87 U0235-87
      Pattern 2 U0104-87 - - - -

      Result

      Result Proceed to
      Pattern 1 A
      Pattern 2 B

    Result: 

    GO TO PRE-COLLISION SYSTEM. Refer to  DTC U0235-87: Lost Communication with Cruise Control Front Distance Range Sensor Missing Message [01/2023 - ] 

    Result: 

    See step  2

  2. CHECK FORWARD RECOGNITION CAMERA 
    GTY1138066Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Millimeter Wave Radar Sensor Assembly)
    1. Disconnect the millimeter wave radar sensor assembly connector.
    2. Using an oscilloscope, check the waveform.

      OK

      Tester Connection Condition Tool Setting Specified Condition
      B9-5 (CA1P) - B9-6 (CA1N) Engine switch on (IG) 1V/DIV., 100μs./DIV. Pulse generation

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY. Refer to  REMOVAL [01/2023 - ] 

    Result: 

    NG 

    REPLACE FORWARD RECOGNITION CAMERA. Refer to  REMOVAL [01/2023 - ]