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Home >> Toyota >> 2017 >> 4Runner TRD Pro >> Repair and Diagnosis >> Brakes >> Anti-Lock Brakes >> Vehicle Stability Control System (For Hydraulic Brake Booster) - Diagnostic Codes (C1422-U0073) & Symptom Tests >> VEHICLE STABILITY CONTROL SYSTEM (for Hydraulic Brake Booster) >> A-TRAC Indicator Light Remains ON [08/2015 - ] >> Procedure

A-TRAC Indicator Light Remains ON [08/2015 - ]: Procedure

  1. CHECK CAN COMMUNICATION LINE 
    1. Turn the ignition switch off.
    2. Connect the Techstream to the DLC3.
    3. Turn the ignition switch to ON.
    4. Turn the Techstream on.
    5. Select CAN Bus Check from the System Selection Menu screen and follow the prompts on the screen to inspect the CAN bus (Refer to DIAGNOSIS SYSTEM [08/2015 - 08/2019] , or refer to DIAGNOSIS SYSTEM [08/2019 - 08/2021] , or refer to DIAGNOSIS SYSTEM [08/2021 - 08/2022] , or refer to DIAGNOSIS SYSTEM [08/2022 - ] ).

      OK

      CAN Bus Check indicates no malfunctions in CAN communication.

    Result: 

    NG 

    GO TO CAN COMMUNICATION SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING) 

    (Refer to HOW TO PROCEED WITH TROUBLESHOOTING [08/2015 - 08/2019] , or refer to HOW TO PROCEED WITH TROUBLESHOOTING [08/2019 - ] )

    Result: 

    OK 

    See step  2

  2. INSPECT TRACTION CONTROL SWITCH (A-TRAC SWITCH) 
    1. Remove the A-TRAC switch (Refer to REMOVAL [08/2015 - ] ).
    2. Measure the resistance according to the value(s) in the table below.
      GTY717030Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Switch Condition Specified Condition
      8 (ATRC) - 5 (E) Pushed in Below 1 Ω
      Not pushed in 10 kΩ or higher
      TEXT IN ILLUSTRATION

      *a Component without harness connected
      (A-TRAC Switch)

    Result: 

    NG 

    REPLACE TRACTION CONTROL SWITCH (A-TRAC SWITCH) 

    (Refer to REMOVAL [08/2015 - ] )

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - A-TRAC SWITCH) 
    1. Disconnect the A6 skid control ECU connector.
    2. Disconnect the U3 A-TRAC switch connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A6-13 (ATRC) - U3-8 (ATRC) Always Below 1 Ω
      A6-13 (ATRC) - Body ground Always 10 k Ω or higher
      U3-5 (E) - Body ground Always Below 1 Ω

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. READ VALUE USING TECHSTREAM (A-TRAC INDICATOR LIGHT) 
    1. Turn the ignition switch off.
    2. Connect the Techstream to the DLC3.
    3. Turn the ignition switch to ON.
    4. Turn the Techstream on.
    5. Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.
    6. Check the condition of the A-TRAC switch by operating the Techstream.
      ABS/VSC/TRAC

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      A-TRAC Indicator Light A-TRAC indicator light/ ON or OFF ON: Indicator light on
      ON: Indicator light off      		 -

      OK

      The Techstream displays ON or OFF according to A-TRAC switch operation.

    Result: 

    OK 

    GO TO METER / GAUGE SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING) 

    (Refer to HOW TO PROCEED WITH TROUBLESHOOTING [08/2015 - ] )

    Result: 

    NG 

    REPLACE MASTER CYLINDER SOLENOID 

    (Refer to DISASSEMBLY [08/2015 - ] )

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