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Home >> Lexus >> 2019 >> ES 350 Luxury >> Repair and Diagnosis >> External Pages >> Different car >> Section 234 (Can Communication System (Hybrid) - Circuit Tests (1 Of 4) & Diagnostic Codes) >> CAN COMMUNICATION SYSTEM (for HV Model) >> Headlight ECU LH Communication Stop Mode [07/2019 - 10/2019] >> Procedure

Headlight ECU LH Communication Stop Mode [07/2019 - 10/2019]: Procedure

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2024 Lexus ES 300h, 2023 Lexus ES 300h, 2022 Lexus ES 300h, 2021 Lexus ES 300h, and 2020 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK FOR OPEN IN CAN BUS LINES (HEADLIGHT ECU SUB-ASSEMBLY LH BRANCH LINE) 
    1. Disconnect the cable from the negative (-) auxiliary battery terminal.
    2. Disconnect the A11 or A78 headlight ECU sub-assembly LH connector.
    3. Measure the resistance according to the value(s) in the table below.
      GTY954658Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *A for TMMK Made Before Sep. 2019 Production
      *B for TMC Made or TMMK Made From Sep. 2019 Production
      *a Front view of wire harness connector
      (to Headlight ECU Sub-assembly LH)

      Standard Resistance

      FOR TMMK MADE BEFORE SEP. 2019 PRODUCTION:

      Tester Connection Condition Specified Condition
      A11-24 (CANH) - A11-23 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω
      FOR TMC MADE OR TMMK MADE FROM SEP. 2019 PRODUCTION:

      Tester Connection Condition Specified Condition
      A78-24 (CANH) - A78-23 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω

      Result

      Result 
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (HEADLIGHT ECU SUB-ASSEMBLY LH) 

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) 
    1. Measure the resistance according to the value(s) in the table below.
      GTY954717Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *A for TMMK Made Before Sep. 2019 Production
      *B for TMC Made or TMMK Made From Sep. 2019 Production
      *a Front view of wire harness connector
      (to Headlight ECU Sub-assembly LH)

      Standard Resistance

      FOR TMMK MADE BEFORE SEP. 2019 PRODUCTION:

      Tester Connection Condition Specified Condition
      A11-12 (GND) - Body ground Cable disconnected from negative (-) auxiliary battery terminal Below 1 Ω
      FOR TMC MADE OR TMMK MADE FROM SEP. 2019 PRODUCTION:

      Tester Connection Condition Specified Condition
      A78-12 (GND) - Body ground Cable disconnected from negative (-) auxiliary battery terminal Below 1 Ω
    2. Reconnect the cable to the negative (-) auxiliary battery terminal.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      FOR TMMK MADE BEFORE SEP. 2019 PRODUCTION:

      Tester Connection Condition Specified Condition
      A11-4 (IG) - Body ground Power switch on (IG) 11 to 14 V
      FOR TMC MADE OR TMMK MADE FROM SEP. 2019 PRODUCTION:

      Tester Connection Condition Specified Condition
      A78-4 (IG) - Body ground Power switch on (IG) 11 to 14 V

      Result

      Result 
      OK
      NG

    Result: 

    OK 

    REPLACE HEADLIGHT ECU SUB-ASSEMBLY LH. Refer to  REMOVAL [06/2018 - 09/2022] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT) 

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