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Engine Stop and Start ECU Communication Stop Mode [08/2023 - ]: Procedure

WARNING: This page is about a different car, the 2025 Lexus RX 350, 2024 Lexus RX 350, and 2023 Lexus RX 350. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK FOR OPEN IN CAN BUS LINES (ENGINE STOP AND START ECU BRANCH LINE) 
    1. Disconnect the cable from the negative (-) battery terminal.
    2. Disconnect the C36 engine stop and start ECU connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      C36-13 (CANH) - C36-14 (CANL) Cable disconnected from negative (-) battery terminal 54 to 69 Ω

      Result

      Proceed to 
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (ENGINE STOP AND START ECU) 

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) 
    1. Disconnect the A24 and A25 engine stop and start ECU connectors.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A24-8 (GND1) - Body ground Cable disconnected from negative (-) battery terminal Below 1 Ω
      A24-2 (GND2) - Body ground Cable disconnected from negative (-) battery terminal Below 1 Ω
      A25-6 (DGND) - Body ground Cable disconnected from negative (-) battery terminal Below 1 Ω
    3. Reconnect the cable to the negative (-) battery terminal.
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A25-1 (+B) - Body ground Ignition switch ON 9.5 to 14 V
      C36-18 (IGP) - Body ground Ignition switch ON 9.5 to 14 V
      C36-21 (IGR) - Body ground Ignition switch ON 9.5 to 14 V
      C36-19 (ACC) - Body ground Ignition switch ACC 9.5 to 14 V
      A24-3 (BIN1) - Body ground Always 9.5 to 14 V
      A24-1 (BIN2) - Body ground Always 9.5 to 14 V

      Result

      Proceed to 
      OK
      NG

    Result: 

    OK 

    REPLACE ENGINE STOP AND START ECU. Refer to  REMOVAL [10/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT) 

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