VEHICLE STABILITY CONTROL SYSTEM Brake Warning Light Remains ON

DESCRIPTION

The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication.

If any of the following is detected, the brake system warning light (red indicator) remains on:


WIRING DIAGRAM

B0086C0E04

CAUTION / NOTICE / HINT

Note


  • When replacing the skid control ECU (brake actuator assembly), perform system variant learning and acceleration sensor zero point calibration.

    Click here

  • Inspect the fuses for circuits related to this system before performing the following procedure.

  • Before performing this procedure, depress the brake pedal and confirm that the stop lights illuminate.

PROCEDURE


  1. CHECK CAN COMMUNICATION SYSTEM


    1. Check if CAN communication system DTCs are output.

      Click here

      Result
      Result Proceed to
      DTCs are not output A
      DTCs are output B

    B

    INSPECT CAN COMMUNICATION SYSTEM Click here

    A

  2. CHECK IF BRAKE ACTUATOR ASSEMBLY CONNECTOR IS SECURELY CONNECTED


    1. Check if the skid control ECU (brake actuator assembly) connector is securely connected.

      OK
      The connector is securely connected.
      Result
      Proceed to
      OK
      NG

    NG

    CONNECT CONNECTOR TO BRAKE ACTUATOR ASSEMBLY CORRECTLY

    OK

  3. CHECK BATTERY


    1. Check the battery voltage.

      Standard Voltage
      Tester Connection Condition Specified Condition
      Positive (+) terminal - Negative (-) terminal Ignition switch off 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY for 2AR-FE: Click here
    CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY for A25A-FKS: Click here
    CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY for 2GR-FKS: Click here

    OK

  4. CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL)


    1. B008807C69
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

      Turn the ignition switch off.

    2. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK
      The connector is securely connected.

    3. Disconnect the A34 skid control ECU (brake actuator assembly) connector.

    4. Check both the connector case and the terminals for deformation and corrosion.

      OK
      No deformation or corrosion.

    5. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A34-30 (+BS) - Body ground Always 11 to 14 V
      A34-36 (IG1) - Body ground Ignition switch ON 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

    OK

  5. CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)


    1. B008807C70
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

      Turn the ignition switch off.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A34-46 (GND1) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

    OK

  6. INSPECT BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY


    1. B0083QWC21
      *a

      Component without harness connected

      (Brake Fluid Level Warning Switch (Brake Master Cylinder Reservoir Assembly))

      Turn the ignition switch off.

    2. Reconnect the A34 skid control ECU (brake actuator assembly) connector.

    3. Remove the reservoir filler cap and strainer.

    4. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK
      The connector is securely connected.

    5. Disconnect the A1 brake fluid level warning switch (brake master cylinder reservoir assembly) connector.

    6. Check both the connector case and the terminals for deformation and corrosion.

      OK
      No deformation or corrosion.

    7. Measure the resistance according to the value(s) in the table below.

      Tech Tips

      A float is located inside the reservoir. Its position changes according to the brake fluid level.

      Standard Resistance
      Tester Connection Condition Specified Condition
      1 (+) - 2 (E) Switch off (float up) 1.9 to 2.1 kΩ
      1 (+) - 2 (E) Switch on (float down) Below 1 Ω

      Tech Tips

      If there is no problem after finishing the above check, adjust the brake fluid level to the MAX level.

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY for LHD: Click here
    REPLACE BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY for RHD: Click here

    OK

  7. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY)


    1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK
      The connector is securely connected.

    2. Disconnect the K21 combination meter assembly connector.

    3. Check both the connector case and the terminals for deformation and corrosion.

      OK
      No deformation or corrosion.

    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      K21-12 (SW) - A1-1 (+) Always Below 1 Ω
      K21-12 (SW) or A1-1 (+) - Body ground Always 10 kΩ or higher
      A1-2 (E) - Body ground Always Below 1 Ω
      Result
      Result Proceed to
      OK (except 2AR-FE) A
      OK (for 2AR-FE) B
      NG C

    B

    READ VALUE USING GTS (BRAKE WARNING LIGHT) Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

  8. INSPECT VACUUM WARNING SWITCH ASSEMBLY


    1. Reconnect the A1 brake fluid level warning switch (brake master cylinder reservoir assembly) connector.

    2. Reconnect the K21 combination meter assembly connector.

    3. Inspect the vacuum warning switch assembly.

      Click here

      OK
      The vacuum warning switch assembly is normal.
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE VACUUM WARNING SWITCH ASSEMBLY

    OK

  9. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - VACUUM WARNING SWITCH ASSEMBLY)


    1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK
      The connector is securely connected.

    2. Disconnect the A2 vacuum warning switch assembly connector.

    3. Disconnect the K21 combination meter assembly connector.

    4. Check both the connector case and the terminals for deformation and corrosion.

      OK
      No deformation or corrosion.

    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      K21-7 (VCM) - A2-2 (+) Always Below 1 Ω
      K21-7 (VCM) or A2-2 (+) - Body ground Always 10 kΩ or higher
      A2-1 (E) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. READ VALUE USING GTS (BRAKE WARNING LIGHT)


    1. Reconnect the A2 vacuum warning switch assembly connector.

    2. Reconnect the K21 combination meter assembly connector.

    3. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.


      Chassis > ABS/VSC/TRC > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Brake Warning Light Brake system warning light (red indicator) ON or OFF

      ON: Warning light on

      OFF: Warning light off

      		 -

      Chassis > ABS/VSC/TRC > Data List
      Tester Display
      Brake Warning Light

    4. Check the GTS display condition of the brake system warning light (red indicator).

      Result
      Result Proceed to
      The value of Brake Warning Light is ON A
      The value of Brake Warning Light is OFF B

    A

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here

    B

    INSPECT METER / GAUGE SYSTEM Click here

  11. READ VALUE USING GTS (BRAKE WARNING LIGHT)


    1. Reconnect the K21 combination meter assembly connector.

    2. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.


      Chassis > ABS/VSC/TRC > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Brake Warning Light Brake system warning light (red indicator) ON or OFF

      ON: Warning light on

      OFF: Warning light off

      		 -

      Chassis > ABS/VSC/TRC > Data List
      Tester Display
      Brake Warning Light

    3. Check the GTS display condition of the brake system warning light (red indicator).

      Result
      Result Proceed to
      The value of Brake Warning Light is ON A
      The value of Brake Warning Light is OFF B

    A

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here

    B

    INSPECT METER / GAUGE SYSTEM Click here