ELECTRONICALLY CONTROLLED BRAKE 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

B006CSAE01

CAUTION / NOTICE / HINT

Note

When replacing the skid control ECU (brake actuator assembly), perform zero point calibration and store system information.

Click here

PROCEDURE


  1. CHECK IF SKID CONTROL ECU 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 ECU CORRECTLY

    OK

  2. CHECK CAN COMMUNICATION SYSTEM


    1. Check if CAN communication system DTCs are output.

      Click here

      Result
      Proceed to
      DTC is not output
      DTC is output

    DTC is output

    CHECK CAN COMMUNICATION SYSTEM Click here

    DTC is not output

  3. INSPECT BATTERY


    1. Check the battery voltage.

      Standard voltage
      11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK OR REPLACE CHARGING SYSTEM OR BATTERY Click here

    OK

  4. CHECK TERMINAL VOLTAGE (IG1 TERMINAL)


    1. Disconnect the A9 skid control ECU (brake actuator assembly) connector.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A9-12 (IG1) - Body ground Engine switch on (IG) 10.5 to 16 V
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT STOP AND START SYSTEM (BACKUP BOOST CONVERTER CIRCUIT) Click here

    OK

  5. CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)


    1. Turn the engine switch off.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A9-25 (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. B006GK2C05
      *a

      Component without harness connected

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

      Turn the engine switch off.

    2. Remove the reservoir filler cap and strainer.

    3. Disconnect the A18 brake fluid level warning switch (brake master cylinder reservoir assembly) connector.

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

      Tech Tips

      A float is located inside the reservoir. Its position can be changed by increasing or decreasing the level of brake fluid.

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      A18-1 (+) - A18-2 (E) Switch off (Float up) 10 kΩ or higher
      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 (BRAKE WARNING LIGHT CIRCUIT)


    1. Disconnect the G34 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G34-17 (SW) or A18-1 (+) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. INSPECT VACUUM WARNING SWITCH ASSEMBLY


    1. Reinstall the reservoir filler cap and strainer.

    2. Reconnect the A18 brake fluid level warning switch (brake master cylinder reservoir assembly) connector.

    3. Reconnect the G34 combination meter assembly connector.

    4. 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 Click here

    OK

  9. CHECK HARNESS AND CONNECTOR (BRAKE WARNING LIGHT CIRCUIT)


    1. Disconnect the G34 combination meter assembly connector.

    2. Disconnect the A4 vacuum warning switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G34-23 (IND) or A4-2 (+) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. CHECK FOR STOP AND START SYSTEM


    1. Reconnect the A9 skid control ECU (brake actuator assembly) connector.

    2. Reconnect the G34 combination meter assembly connector.

    3. Reconnect the A4 vacuum warning switch assembly connector.

    4. Connect the GTS to the DLC3.

    5. Turn the engine switch on (IG).

    6. Turn the GTS on.

    7. Enter the following menus: Powertrain / Stop and Start / Trouble Codes.

    8. Check for DTCs.


      Powertrain > Stop and Start > Trouble Codes
      Result
      Proceed to
      DTCs are not output
      DTCs are output

    DTCs are output

    GO TO STOP AND START SYSTEM (DIAGNOSTIC TROUBLE CODE CHART) Click here

    DTCs are not output

  11. READ VALUE USING GTS (BRAKE SYSTEM WARNING LIGHT (RED INDICATOR))


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

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

    5. According to the display on the GTS, read the 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) OFF or ON

      OFF: Warning light off

      ON: Warning light on

      		 -

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

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

      Result
      Proceed to
      Display of the Data List remains OFF
      Display of the Data List remains ON

    Display of the Data List remains OFF

    INSPECT METER / GAUGE SYSTEM Click here

    Display of the Data List remains ON

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