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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 118 (Can Communication System (HV) - Circuit Tests (1 Of 9) & Diagnostic Codes) >> CAN COMMUNICATION SYSTEM (for HV Model) >> Brake Booster (Skid Control ECU) Communication Stop Mode [12/2019 - 11/2023] >> Procedure

Brake Booster (Skid Control ECU) Communication Stop Mode [12/2019 - 11/2023]: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. CHECK FOR OPEN IN CAN BUS LINES (NO. 1 SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) BRANCH LINE) 
    1. Disconnect the cable from the negative (-) auxiliary battery terminal.
    2. Disconnect the A44 No. 1 skid control ECU (brake booster with master cylinder assembly) connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A44-38 (CA1H) - A44-39 (CA1L) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω
      A44-35 (CA2H) - A44-36 (CA2L) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω
      GTY938818Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to No. 1 Skid Control ECU (Brake Booster with Master Cylinder Assembly))

      Result

      Result 
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (NO. 1 SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY)) 

    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.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A44-28 (GND1) - Body ground Cable disconnected from negative (-) auxiliary battery terminal Below 1 Ω
      GTY895591Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to No. 1 Skid Control ECU (Brake Booster with Master Cylinder Assembly))
    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

      Tester Connection Condition Specified Condition
      A44-14 (+BI1) - Body ground Ignition switch off 11 to 14 V
      A44-31 (IG1) - Body ground Ignition switch ON 11 to 14 V
      A44-42 (IG2) - Body ground Ignition switch ON 11 to 14 V

      Result

      Result 
      OK
      NG

    Result: 

    OK 

    REPLACE NO. 1 SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) 

    Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT) 

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