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ELECTRONICALLY CONTROLLED BRAKE SYSTEM Brake Warning Light Remains ON

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DTC Code DTC Name
  Brake Warning Light Remains ON
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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:


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WIRING DIAGRAM


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  1. A0005UWE11

    for LHD

  2. A0005UWE12

    for RHD

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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.

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PROCEDURE


  1. Click here

    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

  2. Click here

    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

  3. Click here

    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.

    • OKClick here
    • NG

      CONNECT CONNECTOR TO BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY CORRECTLY

  4. Click here

    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

    • OKClick here
    • NG

      CHARGE OR REPLACE AUXILIARY BATTERY

  5. Click here

    CHECK HARNESS AND CONNECTOR (IG1 TERMINAL)


    1. A0009HJE01

      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
      Table 1. Text in Illustration
      *a

      Front view of wire harness connector

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

    • OKClick here
    • NG

      REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

  6. Click here

    CHECK HARNESS AND CONNECTOR (GND TERMINAL)


    1. A0006UCE01

      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
      Table 2. Text in Illustration
      *a

      Front view of wire harness connector

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

    • OKClick here
    • NG

      REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

  7. Click here

    READ VALUE USING GTS (PARKING BRAKE SWITCH ASSEMBLY)


    1. Reconnect the A24 skid control ECU (brake booster with master cylinder assembly) 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).

      Table 3. ABS/VSC/TRC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Parking Brake SW Parking brake switch assembly / ON or OFF

      ON: Parking brake applied

      OFF: Parking brake released

      		 -

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

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

  8. Click here

    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
      Tip:

      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)

  9. Click here

    INSPECT PARKING BRAKE SWITCH ASSEMBLY


    1. A0005PJE10

      Turn the power switch off.

    2. Disconnect the A35 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 assembly ON

      (Switch pin free)

      		 Below 1 Ω
      1 (+) - Body ground

      Parking brake switch assembly OFF

      (Switch pin pushed in)

      		 10 kΩ or higher
      Table 4. Text in Illustration
      *a

      Component without harness connected

      (Parking Brake Switch Assembly)
      Result
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

  10. Click here

    CHECK HARNESS AND CONNECTOR (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) - PARKING BRAKE SWITCH ASSEMBLY)


    1. Disconnect the 3D main body ECU (multiplex network body ECU) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3D-20 (PKB) - A35-1 (+) Always Below 1 Ω
      3D-20 (PKB) - Body ground Always 10 kΩ or higher
      Tip:

      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).


    • OK

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

    • NG

      REPAIR OR REPLACE HARNESS OR CONNECTOR