ELECTRONICALLY CONTROLLED BRAKE SYSTEM Brake Warning Light Remains ON

DESCRIPTION

The skid control ECU is connected to the combination meter via CAN communication.

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


WIRING DIAGRAM

A0043FVE11

INSPECTION PROCEDURE

Note

When replacing the brake booster with master cylinder (skid control ECU), perform initialization, calibration of the linear solenoid valve and emergency brake signal learning Click here.

PROCEDURE


  1. CHECK DTC


    1. Check if a ABS, VSC and/or electronically controlled brake system DTC is output Click here.

      Result
      Result Proceed to
      DTC is not output A
      DTC is output B

    B

    REPAIR CIRCUITS INDICATED BY OUTPUT DTCS Click here

    A

  2. CHECK CAN COMMUNICATION SYSTEM


    1. Check if a CAN communication system DTC is output Click here.

      Result
      Result Proceed to
      DTC is not output A
      DTC is output B

    B

    INSPECT CAN COMMUNICATION SYSTEM Click here

    A

  3. CHECK IF SKID CONTROL ECU CONNECTOR IS SECURELY CONNECTED


    1. Check if the skid control ECU connector is securely connected.

      OK
      The connector is securely connected.

    NG

    CONNECT CONNECTOR TO ECU CORRECTLY

    OK

  4. CHECK AUXILIARY BATTERY


    1. Check the auxiliary battery voltage.

      Standard Voltage
      11 to 14 V

    NG

    CHARGE OR REPLACE AUXILIARY BATTERY

    OK

  5. INSPECT SKID CONTROL ECU (IG1 TERMINAL)


    1. A0044BAE81
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU)

      Disconnect the A57 skid control ECU connector.

    2. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A57-16 (IG1) - Body ground Power switch on (IG) 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

    OK

  6. INSPECT SKID CONTROL ECU (GND TERMINAL)


    1. A0044BAE75
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU)

      Turn the power switch off.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A57-28 (GND) - Body ground Always Below 1 Ω
      A57-27 (GND2) - Body ground Always Below 1 Ω
      A57-26 (GND3) - Body ground Always Below 1 Ω
      A57-25 (GND4) - Body ground Always Below 1 Ω
      A57-24 (GND5) - Body ground Always Below 1 Ω
      A57-23 (GND6) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

    OK

  7. READ VALUE USING GTS (PARKING BRAKE SWITCH)


    1. Reconnect the A57 skid control ECU connector.

    2. Connect the GTS to the DLC3.

    3. Turn the power switch on (IG).

    4. Select the Data List on the GTS Click here.

      ABS/VSC/TRC
      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

      		 -

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

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

    NG

    INSPECT PARKING BRAKE SWITCH Click here

    OK

  8. INSPECT COMBINATION METER


    1. Turn the power switch off.

    2. Perform the Active Test of the combination meter (meter CPU) using the GTS Click here.

    3. Check the combination meter.

      OK
      The brake warning light / red (malfunction) turns on or off in accordance with the GTS operation.
      Result
      Result Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG C

      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 the part Click here.


    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER Click here

    C

    REPLACE NO. 3 METER CIRCUIT PLATE Click here

    A

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER Click here

  9. INSPECT PARKING BRAKE SWITCH


    1. A0042EJE03
      Text in Illustration
      *a

      Component without harness connected

      (Parking Brake Switch)

      Turn the power switch off.

    2. Disconnect the A25 parking brake switch 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
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

    B

    REPLACE PARKING BRAKE SWITCH Click here

    C

    REPLACE PARKING BRAKE SWITCH Click here

    A

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


    1. Disconnect the 2C main body ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      2C-20 (PKB) - A25-1 (+) Always Below 1 Ω
      2C-20 (PKB) - 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 the part Click here.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK) Click here