ANTI-LOCK BRAKE SYSTEM Brake Warning Light Circuit

DESCRIPTION

The brake warning light lights up when there is insufficient brake fluid, the parking brake is applied or the EBD is defective.

WIRING DIAGRAM

A0138A7E01

INSPECTION PROCEDURE

Tech Tips

Before releasing the parking brake, set chocks to hold the vehicle for safety.

PROCEDURE


  1. CHECK BRAKE FLUID LEVEL


    1. Check the amount of brake fluid in the brake reservoir.

      OK
      Brake fluid level is correct.

    NG

    ADD BRAKE FLUID

    OK

  2. CHECK FOR DTC


    1. Check if any DTCs are output.

      Result
      DTC output A
      DTC not output B

    B

    CHECK BRAKE WARNING LIGHT Click here

    A

    REPAIR CIRCUIT INDICATED BY OUTPUT DTC

  3. CHECK BRAKE WARNING LIGHT


    1. When using an intelligent tester:


      1. Connect the intelligent tester to the DLC3.

      2. Turn the ignition switch to the ON position.

      3. Turn the tester ON.

      4. Select the "Brake Warning Light" in the ACTIVE TEST and operate the brake warning light by using the intelligent tester.

        Select the following menu items: Chassis / ABS/VSC/TRC / Active Test.

        Item Vehicle Condition / Test Details Diagnostic Note
        Brake Warning Light Turns brake warning light ON / OFF Observe combination meter

      5. Check that "ON" and "OFF" of the brake warning light are indicated on the combination meter when using the intelligent tester.

        OK
        The brake warning light turns ON or OFF in accordance with the intelligent tester.

    2. When not using an intelligent tester.

      Tech Tips

      By disconnecting the skid control ECU connector, the brake warning light comes on (as the brake warning circuit in the meter is an active circuit).


      1. Turn the ignition switch OFF.

      2. Disconnect the skid control ECU connector.

      3. Turn the ignition switch to the ON position.

      4. Check that the brake warning light comes on.

        OK
        The brake warning light comes on.

    NG

    INSPECT PARKING BRAKE SWITCH ASSEMBLY Click here

    OK

    REPLACE BRAKE ACTUATOR

  4. INSPECT PARKING BRAKE SWITCH ASSEMBLY


    1. Remove the parking brake switch Click here.

    2. A0136WCE01

      Measure the resistance.

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      H18-1 - Ground part Released Below 1 Ω
      H18-1 - Ground part Pushed in 10 kΩ or higher

    NG

    REPLACE PARKING BRAKE SWITCH ASSEMBLY

    OK

  5. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - PARKING BRAKE SWITCH)


    1. Disconnect the skid control ECU connector and the parking brake switch connector.

    2. A0135VJE01

      Measure the resistance.

      Standard Resistance
      Tester Connection Specified Condition
      A21-14 (PKB) - H18-1 Below 1 Ω
      A21-14 (PKB) - Body ground 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

  6. INSPECT BRAKE FLUID LEVEL WARNING SWITCH


    1. Disconnect the brake fluid level warning switch connector.

    2. A0138BLE01

      Measure the resistance.

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      A12-1 (+) - A12-2 (E) Float UP 10 kΩ or higher
      A12-1 (+) - A12-2 (E) Float DOWN Below 1 Ω

    NG

    REPLACE MASTER CYLINDER RESERVOIR

    OK

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


    1. Disconnect the combination meter connector and the brake fluid level warning switch connector.

    2. A0135WLE01

      Measure the resistance.

      Standard Resistance
      Tester Connection Specified Condition
      A22-13 (SW) - A12-1 (+) Below 1 Ω
      A22-13 (SW) - Body ground 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

  8. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - COMBINATION METER)


    1. Disconnect the combination meter connector and the combination meter connector.

    2. A013742E02

      Measure the resistance.

      Standard Resistance
      Tester Connection Specified Condition
      A21-12 (EBDW) - A22-15 (EBD) Below 1 Ω
      A21-12 (EBDW) - Body ground 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

  9. INSPECT COMBINATION METER ASSEMBLY


    1. Turn the ignition switch to the ON position.

    2. A0138EGE04

      Measure the voltage.

      Standard Voltage
      Tester Connection Specified Condition
      A22-15 (EBD) - Body ground 5 to 14 V

    NG

    REPLACE COMBINATION METER ASSEMBLY

    OK

    REPLACE BRAKE ACTUATOR