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Home › Subaru › 2020 › BRZ Limited, Automatic Trans › Repair and Diagnosis › Brakes › Traction Control › Vehicle Stability Control (VSC) System › Vehicle Stability Control System › Brake Warning Light Remains ON › Inspection steps

Inspection steps

CAUTION:
  • When the skid control computer (brake actuator ASSY) has been replaced, make sure to perform [VSC(VDC) Centering Mode]. (Refer to WORK SUPPORT )
  • Before performing troubleshooting, check the fuse for this circuit.
  1. Preliminary inspection
    1. Make sure that the following conditions for turning off the brake warning light are met.
      1. The ABS warning light is OFF.
      2. The brake fluid is sufficient in the brake master cylinder reservoir.
      3. The parking brake is completely released.
    2. Inspection of connection for each part
      1. Lightly shake the connectors and the wiring harness at eat part up/down/left/right, to check the illumination status for the brake warning light.

        Criteria: The brake warning light status does not change. 

        NOTE: If the warning light illumination status changes when shaking the connectors and the wires of the skid control computer (brake actuator ASSY), check the terminals for poor connections.

        OK: Go to next step

        NG: Repair or replacement of wiring harness or connector

    3. Diagnostic code check (CAN communication system)
      1. Check CAN communication system. (Refer to HOW TO TROUBLESHOOT )
        RESULT DESCRIPTION

        Result Go to
        No output A
        Output exists B
        1. Go to next step
        2. Go to "CAN communication system (How to troubleshoot)" (Refer to HOW TO TROUBLESHOOT )
    4. Check wiring harness and connector (+BS, IG1, GND1, GND2 terminals)
      1. Check the connector of the skid control computer (brake actuator ASSY) for a trouble such as poor engagement or disconnection.

        Criteria: No trouble 

      2. Turn IG OFF and disconnect the connector A5 from the skid control computer (brake actuator ASSY).
      3. Check the case and terminal of the connector for deformation and/or corrosion.

        Criteria: No deformation or corrosion. 

      4. Check the voltage and resistance between terminals.

        Voltage 

        STANDARD VALUE SPECIFICATION

        Inspection terminals Inspection conditions Standard value
        A5-25(+BS) - chassis ground Always 11 to 14V
        A5-28(IG1) - chassis ground IG ON 11 to 14V

        Resistance 

        Inspection terminals Inspection conditions Standard value
        A5-38(GND1) - chassis ground Always Less than 1 Ω
        A5-13(GND2) - chassis ground Always Less than 1 Ω
        G12590977Courtesy of SUBARU OF AMERICA, INC.
        NOTE: If there is a malfunction in GND1 and GND2 terminals, check the ground point for looseness.

        OK: Go to next step

        NG: Repair or replacement of wiring harness or connector

    5. Parking brake switch ASSY check
      1. Check the parking brake switch ASSY. (Refer to UNIT INSPECTION )

        OK: Go to next step

        NG: Replacement of parking brake switch ASSY (Refer to PARKING BRAKE SWITCH ASSY )

    6. Check wiring harness and connector (Main body ECM (network gateway computer) - parking brake switch ASSY)
      1. Turn IG OFF and disconnect the connector (3B) for the main body ECM (network gateway computer).
      2. Disconnect the connector, D31 for the parking brake switch ASSY.
      3. Measure the resistance between the terminals.

        Resistance 

        Inspection terminals Inspection conditions Standard value
        3B-24 - D31-1 Always Less than 1 Ω
        3B-24 - chassis ground Always 10 k Ω or more

        OK: Go to next step

        NG: Repair or replacement of wiring harness or connector

    7. Brake master cylinder SUB-ASSY check (fluid level warning switch)
      1. With the brake fluid at a specified level, disconnect the connector (A59) for the fluid level warning switch (brake master cylinder reservoir SUB-ASSY), and check the brake warning light status.
        RESULT DESCRIPTION

        Result Go to
        The brake warning light does not go off. A
        The brake warning light goes off. B
        NOTE: If the warning light goes off, the fluid level warning switch (brake master cylinder reservoir SUB-ASSY) is internally shorted.
        1. Go to next step
        2. Replacement of brake master cylinder SUB-ASSY (Refer to BRAKE MASTER CYLINDER ASSY )
    8. Check wiring harness and connector (fluid level warning switch - combination meter ASSY and chassis ground)
      1. Turn the ignition switch to OFF, and then disconnect the connector (D7) for the combination meter ASSY.
      2. Measure the resistance between the terminals.

        Resistance 

        Inspection terminals Inspection conditions Standard value
        A59-1 - D7-17(LBL) Always Less than 1 Ω
        A59-1 - chassis ground Always 10 k Ω or more
        A59-2 - chassis ground Always Less than 1 Ω

        OK: Go to next step

        NG: Repair or replacement of wiring harness or connector

        To meter & gauge system (How to troubleshoot) (Refer to HOW TO TROUBLESHOOT )

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