ELECTRONICALLY CONTROLLED BRAKE SYSTEM Brake Warning Light Remains ON

DESCRIPTION

The skid control ECU (brake booster with master cylinder assembly) is connected to the combination meter assembly via CAN communication.

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


WIRING DIAGRAM


  1. for LHD

    A0005GJE03

  2. for RHD

    A0005GJE04

CAUTION / NOTICE / HINT

Note


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

  • If the main body ECU (multiplex network body ECU) is replaced, refer to Service Bulletin.

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

PROCEDURE


  1. CHECK DTC


    1. Check if ABS, VSC and/or electronically controlled brake system DTCs are output Click here.

      Result
      Result Proceed to
      DTCs are not output. A
      DTCs are output. B

    B

    REPAIR CIRCUITS INDICATED BY OUTPUT DTCS Click here

    A

  2. CHECK CAN COMMUNICATION SYSTEM


    1. Check if CAN communication system DTCs are output (See page for w/ Central Gateway ECU or Click here for w/o Central Gateway ECU).

      Result
      Result Proceed to
      DTCs are not output. A
      DTCs are output (w/ Central Gateway ECU). B
      DTCs are output (w/o Central Gateway ECU). C

    B

    INSPECT CAN COMMUNICATION SYSTEM Click here

    C

    INSPECT CAN COMMUNICATION SYSTEM Click here

    A

  3. CHECK IF BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY CONNECTOR IS SECURELY CONNECTED


    1. Check if the skid control ECU (brake booster with master cylinder assembly) connector is securely connected.

      OK
      The connector is securely connected.

    NG

    CONNECT CONNECTOR TO BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY CORRECTLY

    OK

  4. CHECK AUXILIARY BATTERY


    1. Check the auxiliary battery voltage.

      Standard Voltage
      Tester Connection Condition Specified Condition
      Auxiliary battery Power switch on (IG) 11 to 14 V
      Auxiliary battery Power switch on (READY) 11 to 15.5 V

    NG

    CHARGE OR REPLACE AUXILIARY BATTERY

    OK

  5. CHECK HARNESS AND CONNECTOR (IG1 TERMINAL)


    1. A0009HJE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Booster with Master Cylinder Assembly))

      Disconnect the A24 skid control ECU (brake booster with master cylinder assembly) 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
      A24-16 (IG1) - Body ground Power switch on (IG) 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

    OK

  6. CHECK HARNESS AND CONNECTOR (GND TERMINAL)


    1. A0006UCE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Booster with Master Cylinder Assembly))

      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
      A24-28 (GND) - Body ground Always Below 1 Ω
      A24-27 (GND2) - Body ground Always Below 1 Ω
      A24-26 (GND3) - Body ground Always Below 1 Ω
      A24-25 (GND4) - Body ground Always Below 1 Ω
      A24-24 (GND5) - Body ground Always Below 1 Ω
      A24-23 (GND6) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

    OK

  7. INSPECT COMBINATION METER ASSEMBLY


    1. Turn the power switch off.

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

    3. Check the combination meter assembly.

      OK
      The brake warning light / red (malfunction) turns on or off in accordance with 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.


    A

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

    C

    REPLACE COMBINATION METER ASSEMBLY Click here