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Home >> Toyota >> 2022 >> Avalon XLE >> Repair and Diagnosis >> External Pages >> Different car >> Section 55 (Pre-Collision System - Diagnostic Codes (Except Hybrid)) >> PRE-COLLISION SYSTEM (for Gasoline Model) >> DTC U1104: Lost Communication with Driving Support ECU [04/2018 - 08/2021] >> Procedure

DTC U1104: Lost Communication with Driving Support ECU [04/2018 - 08/2021]: Procedure

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  1. READ VALUE USING TECHSTREAM (CAN BUS CHECK) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: System Select / Can Bus Check.

      Refer to DIAGNOSIS SYSTEM [04/2018 - 08/2020] , or refer to DIAGNOSIS SYSTEM [08/2020 - 08/2021]

      CAN Bus Check 

      Result

      Result Proceed to
      All of the ECUs and sensors that are currently connected to the CAN communication system are displayed A
      None of the ECUs and sensors that are currently connected to the CAN communication system are displayed, or some of them are not displayed B

    Result: 

    B 

    GO TO CAN COMMUNICATION SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [04/2018 - ] 

    Result: 

    A 

    See step  2

  2. CHECK FOR DTCs 
    1. Check for DTCs.

      Chassis > Front Recognition Camera > Trouble Codes 

      Result

      Result Proceed to
      DTCs are not output A
      Only DTC U0235 is output B
      Only DTC U1104 is output C
      DTC U0235 and U1104 are output D

    Result: 

    B 

    See step  6

    Result: 

    C 

    REPLACE DRIVING SUPPORT ECU ASSEMBLY. Refer to  COMPONENTS [04/2018 - 08/2021] 

    Result: 

    D 

    See step  7

    Result: 

    A 

    See step  3

  3. CHECK FOR DTCs 
    1. Check for DTCs.

      Chassis > ABS/VSC/TRAC/EPB > Trouble Codes 

      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 [04/2018 - 08/2021] 

    Result: 

    A 

    See step  4

  4. TEST MODE INSPECTION (ELECTRONICALLY CONTROLLED BRAKE SYSTEM) 
    NOTE:

    Perform Test Mode (Signal Check) with the vehicle stopped.

    HINT: 

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

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

        HINT: 

        Do not exit Test Mode (Signal Check) within 5 seconds of entering Test Mode (Signal Check). If Test Mode (Signal Check) is exited within 5 seconds of entering Test Mode (Signal Check), DTC U1104 may be stored. If DTC U1104 is output after exiting Test Mode (Signal Check), enter Test Mode (Signal Check) again, wait at least 5 seconds, then recheck for DTCs.

        Chassis > ABS/VSC/TRAC/EPB > Utility 

        Tester Display
        Signal Check
      9. Check that the ABS warning and slip indicator lights come on for several seconds and the ABS warning, slip indicator and parking brake indicator lights blink in the Test Mode pattern.

        HINT: 

        • If the ABS warning, slip indicator and parking brake indicator lights do not blink, inspect the ABS warning, slip indicator and parking brake indicator light circuits.
        • While the parking brake is engaged, the parking brake indicator light illuminates but does not blink in the Test Mode pattern.
    2. End of Test Mode (Signal Check)
      1. End Test Mode (signal check) using the Techstream
        1. Turn the engine switch off and enter normal mode.
        2. Remove the Techstream.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  5

  5. CHECK FOR DTCs 
    1. Clear the DTCs.

      Body Electrical > Pre-Collision 2 > 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 2 > Trouble Codes 

      Result

      Result Proceed to
      DTC U1104 is not output A
      DTC U1104 is output B

    Result: 

    A 

    END 

    Result: 

    B 

    REPLACE DRIVING SUPPORT ECU ASSEMBLY. Refer to  COMPONENTS [04/2018 - 08/2021] 

  6. CHECK CAN BUS LINE 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal.
    3. Disconnect the O5 forward recognition camera connector.
      GTY939013Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Forward Recognition Camera)
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      O5-6 (CANH) - O5-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω

      HINT: 

      If the result is not as specified, a malfunction in a CAN communication line is suspected.

    5. Connect the O5 forward recognition camera connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY. Refer to  COMPONENTS [04/2018 - 08/2021] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (CAN BUS LINE) 

  7. CHECK CAN BUS LINE 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal.
    3. Disconnect the O5 forward recognition camera connector.
      GTY939013Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Forward Recognition Camera)
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      O5-6 (CANH) - O5-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω

      HINT: 

      If the result is not as specified, a malfunction in a CAN communication line is suspected.

    5. Connect the O5 forward recognition camera connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FORWARD RECOGNITION CAMERA. Refer to  COMPONENTS [04/2018 - 08/2021] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (CAN BUS LINE) 

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