VEHICLE STABILITY CONTROL SYSTEM Brake Warning Light Remains ON

DESCRIPTION

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

If any of the following is detected, the brake warning light remains on:


WIRING DIAGRAM

A01QU2RE01

CAUTION / NOTICE / HINT

Note


  • When replacing the skid control ECU (brake actuator assembly), perform zero point calibration.

    Click here

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

  • When replacing the main body ECU (multiplex network body ECU), make sure to replace it with a new one.

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.

      for LHD with Central Gateway ECU: Click here

      for RHD with Central Gateway ECU: Click here

      for LHD without Central Gateway ECU: Click here

      for RHD without Central Gateway ECU: Click here

      Result
      Proceed to
      DTC is not output
      DTC is output (for LHD with Central Gateway ECU)
      DTC is output (for RHD with Central Gateway ECU)
      DTC is output (for LHD without Central Gateway ECU)
      DTC is output (for RHD without Central Gateway ECU)

    DTC is output (for LHD with Central Gateway ECU)

    CHECK CAN COMMUNICATION SYSTEM Click here

    DTC is output (for RHD with Central Gateway ECU)

    CHECK CAN COMMUNICATION SYSTEM Click here

    DTC is output (for LHD without Central Gateway ECU)

    CHECK CAN COMMUNICATION SYSTEM Click here

    DTC is output (for RHD without Central Gateway ECU)

    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 (for 2AD-FHV)
      NG (for 2AD-FTV)
      NG (for 2AR-FE)
      NG (for 3ZR-FAE)
      NG (for 3ZR-FE)
      NG (for 2WW)

    NG (for 2AD-FHV)

    CHECK OR REPLACE CHARGING SYSTEM OR BATTERY Click here

    NG (for 2AD-FTV)

    CHECK OR REPLACE CHARGING SYSTEM OR BATTERY Click here

    NG (for 2AR-FE)

    CHECK OR REPLACE CHARGING SYSTEM OR BATTERY Click here

    NG (for 3ZR-FAE)

    CHECK OR REPLACE CHARGING SYSTEM OR BATTERY Click here

    NG (for 3ZR-FE)

    CHECK OR REPLACE CHARGING SYSTEM OR BATTERY Click here

    NG (for 2WW)

    CHECK OR REPLACE CHARGING SYSTEM OR BATTERY Click here

    OK

  4. CHECK TERMINAL VOLTAGE (IG1 TERMINAL)


    1. A01QPOVC30
      *a

      Front view of wire harness connector

      (to Skid Control ECU [Brake Actuator Assembly])

      Disconnect the A80 skid control ECU (brake actuator assembly) connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A80-12 (IG1) - Body ground Ignition switch ON 11 to 14 V

    4. Turn the ignition switch off.

      Result
      Proceed to
      OK
      NG (w/o Stop and Start System)
      NG (w/ Stop and Start System)

    NG (w/o Stop and Start System)

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

    NG (w/ Stop and Start System)

    INSPECT STOP AND START SYSTEM (BACKUP BOOST CONVERTER CIRCUIT)

    OK

  5. CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)


    1. Turn the ignition switch off.

    2. A01QPOVC26
      *a

      Front view of wire harness connector

      (to Skid Control ECU [Brake Actuator Assembly])

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A80-25 (GND1) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

    OK

  6. READ VALUE USING GTS (PARKING BRAKE SW)


    1. Reconnect the A80 skid control ECU (brake actuator assembly) connector.

    2. Connect the GTS to the DLC3.

    3. Turn the ignition switch to ON.

    4. Turn the GTS on.

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

    6. 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
      Parking Brake SW Parking brake switch assembly OFF or ON

      OFF: Parking brake released

      ON: Parking brake applied

      		 -

      Chassis > ABS/VSC/TRC > Data List
      Tester Display
      Parking Brake SW

    7. Using the GTS, check the input of the switch operation when the parking brake lever is operated.

      OK
      The GTS displays ON or OFF according to parking brake operation.
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT PARKING BRAKE SWITCH ASSEMBLY Click here

    OK

  7. INSPECT BRAKE MASTER CYLINDER RESERVOIR SUB-ASSEMBLY


    1. A01QT03C01
      *a

      Component without harness connected

      (Brake Fluid Level Warning Switch [Brake Master Cylinder Reservoir Sub-assembly])

      Turn the ignition switch off.

    2. Remove the reservoir filler cap and strainer.

    3. Disconnect the A9 brake fluid level warning switch (brake master cylinder reservoir sub-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
      1 - 2 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 (for LHD)
      NG (for RHD)

    NG (for LHD)

    REPLACE BRAKE MASTER CYLINDER RESERVOIR SUB-ASSEMBLY Click here

    NG (for RHD)

    REPLACE BRAKE MASTER CYLINDER RESERVOIR SUB-ASSEMBLY Click here

    OK

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


    1. Disconnect the G16 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G16-12 (SW) - A9-1 Always Below 1 Ω
      A9-2 - Body ground Always Below 1 Ω
      G16-12 (SW) or A9-1 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  9. READ VALUE USING GTS (BRAKE WARNING LIGHT)


    1. Reinstall the reservoir filler cap and strainer.

    2. Reconnect the G16 combination meter assembly connector and the A9 brake fluid level warning switch (brake master cylinder reservoir sub-assembly) connector.

    3. Connect the GTS to the DLC3.

    4. Turn the ignition switch to ON.

    5. Turn the GTS on.

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

    7. 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 warning light OFF or ON

      OFF: Warning light off

      ON: Warning light on

      		 -

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

    8. Check the GTS display condition of the brake warning light.

      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 Click here

  10. INSPECT PARKING BRAKE SWITCH ASSEMBLY


    1. Remove the parking brake switch assembly.

      Click here

    2. Inspect the parking brake switch assembly.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE PARKING BRAKE SWITCH ASSEMBLY Click here

    OK

  11. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - PARKING BRAKE SWITCH ASSEMBLY)


    1. Disconnect the 3D instrument panel junction block assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3D-34 - G37-1 Always Below 1 Ω
      3D-34 or G37-1 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  12. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY


    1. Remove the instrument panel junction block assembly.

      for LHD: Click here

      for RHD: Click here

    2. Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

      for LHD: Click here

      for RHD: Click here

    3. A01QRLKC02
      *a

      Component without harness connected

      (Instrument Panel Junction Block Assembly)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3D-34 - A-12 (PKB) Always Below 1 Ω
      3D-34 or A-12 (PKB) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK (for LHD)
      OK (for RHD)
      NG (for LHD)
      NG (for RHD)

    OK (for LHD)

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here

    OK (for RHD)

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here

    NG (for LHD)

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY Click here

    NG (for RHD)

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY Click here