ANTI-LOCK BRAKE SYSTEM(for Type A) 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 warning light remains on:


WIRING DIAGRAM

A01LYB9E14

CAUTION / NOTICE / HINT

Note

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

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 ECU CORRECTLY

    OK

  3. CHECK BATTERY


    1. Check the battery voltage.

      Standard Voltage
      11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY for 1NR-FE: Click here
    CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY for 1ZR-FE: Click here
    CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY for 1ND-TV: Click here
    CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY for 2ZR-FE: Click here

    OK

  4. CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL)


    1. A01LYMTC01
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

      Disconnect the A120 skid control ECU (brake actuator assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A120-25 (+BS) - Body ground Always 11 to 14 V
      A120-25 (+BS) - A120-38 (GND1) Always 11 to 14 V
      A120-28 (IG1) - Body ground Ignition switch ON 11 to 14 V
      A120-28 (IG1) - A120-38 (GND1) Ignition switch ON 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE TERMINAL)

    OK

  5. CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)


    1. A01LYMTC02
      *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
      A120-38 (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 SWITCH ASSEMBLY)


    1. Reconnect the A120 skid control ECU (brake actuator assembly) connector.

    2. Connect the GTS to the DLC3.

    3. Turn the ignition switch to ON.

    4. Select the Data List using the GTS.

      Click here


      Chassis > ABS/VSC/TRC > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Parking Brake SW Parking brake switch ON or OFF

      ON: Parking brake applied

      OFF: Parking brake released

      		 -

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

    5. Using the GTS, check that the switch condition displayed on the GTS changes according to the parking brake operation.

      OK
      When the parking brake is operated, the display changes as shown above.
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT PARKING BRAKE SWITCH ASSEMBLY Click here

    OK

  7. INSPECT BRAKE FLUID LEVEL WARNING SWITCH


    1. A01M1GDC03
      *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 A156 brake fluid level warning switch 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 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 SUB-ASSEMBLY Click here

    OK

  8. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - BRAKE FLUID LEVEL WARNING SWITCH)


    1. Disconnect the E46 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E46-12 (SW) - A156-1 (+) Always Below 1 Ω
      E46-12 (SW) or A156-1 (+) - Body ground Always 10 kΩ or higher
      A156-2 (E) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  9. INSPECT COMBINATION METER ASSEMBLY


    1. Reconnect the E46 combination meter assembly connector and the A156 brake fluid level warning switch connector.

    2. Perform an Active Test of the combination meter assembly using the GTS.

      Click here


      Body Electrical > Combination Meter > Active Test
      Tester Display
      Indicat. Lamp Brake

    3. Check the combination meter assembly.

      OK
      The brake warning light turns on or off in accordance with the Active Test operation.

      Tech Tips

      If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step before replacing parts.

      Click here

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    NG

    INSPECT METER / GAUGE SYSTEM Click here

  10. INSPECT PARKING BRAKE SWITCH ASSEMBLY


    1. A01LYE8C03
      *a

      Component without harness connected

      (Parking Brake Switch Assembly)

      Turn the ignition switch off.

    2. Disconnect the L18 parking brake switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1 (+) - Body ground Parking brake switch ON (Switch pin free) Below 1 Ω
      1 (+) - Body ground Parking brake switch OFF (Switch pin pushed in) 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE PARKING BRAKE SWITCH ASSEMBLY Click here

    OK

  11. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - PARKING BRAKE SWITCH ASSEMBLY)


    1. Disconnect the 3E main body ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3E-27 (PKB) - L18-1 (+) Always Below 1 Ω
      3E-27 (PKB) or L18-1 (+) - Body ground Always 10 kΩ or higher

      Tech Tips

      If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step before replacing parts.

      Click here

      Result
      Proceed to
      OK
      NG

    OK

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

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR