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

A01KRCLE03

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

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

PROCEDURE


  1. CHECK DTC


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

      Click here


      Chassis > ABS/VSC/TRC > Trouble Codes
      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.

      Click here

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

    B

    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.
      Result
      Proceed to
      OK
      NG

    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
      Result
      Proceed to
      OK
      NG

    NG

    CHARGE OR REPLACE AUXILIARY BATTERY

    OK

  5. CHECK HARNESS AND CONNECTOR (IG1 TERMINAL)


    1. A01KR95C36
      *a

      Front view of wire harness connector

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

      Disconnect the A144 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
      A144-16 (IG1) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

    OK

  6. CHECK HARNESS AND CONNECTOR (GND TERMINAL)


    1. A01KR95C37
      *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
      A144-28 (GND) - Body ground Always Below 1 Ω
      A144-27 (GND2) - Body ground Always Below 1 Ω
      A144-26 (GND3) - Body ground Always Below 1 Ω
      A144-25 (GND4) - Body ground Always Below 1 Ω
      A144-24 (GND5) - Body ground Always Below 1 Ω
      A144-23 (GND6) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

    OK

  7. READ VALUE USING GTS (PARKING BRAKE SWITCH ASSEMBLY)


    1. Reconnect the A144 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


      Chassis > ABS/VSC/TRC > Data List
      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

      		 -

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

    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.
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT PARKING BRAKE SWITCH ASSEMBLY Click here

    OK

  8. READ VALUE USING GTS (BRAKE WARNING LIGHT / RED (MALFUNCTION))


    1. Select the Data List on the GTS.

      Click here


      Chassis > ABS/VSC/TRC > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Brake Warning Light Brake warning light / red (malfunction) ON or OFF

      ON: Warning light on

      OFF: Warning light off

      		 -

      Chassis > ABS/VSC/TRC > Data List
      Tester Display
      Brake Warning Light

    2. Check the GTS display condition of the brake warning light / red (malfunction).

      Result
      Result Proceed to
      Display of the Data List remains OFF. A
      Display of the Data List remains ON. B

      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 parts.

      Click here


    A

    INSPECT METER / GAUGE SYSTEM Click here

    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY for LHD: Click here
    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY for RHD: Click here

  9. INSPECT PARKING BRAKE SWITCH ASSEMBLY


    1. A01KU2EC06
      *a

      Component without harness connected

      (Parking Brake Switch Assembly)

      Turn the power 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 assembly on

      (Switch pin free)

      		 Below 1 Ω
      1 (+) - Body ground

      Parking brake switch assembly off

      (Switch pin pushed in)

      		 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE PARKING BRAKE SWITCH ASSEMBLY Click here

    OK

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


    1. Disconnect the 3E 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
      3E-27 (PKB) - L18-1 (+) Always Below 1 Ω
      3E-27 (PKB) - Body ground Always 10 kΩ or higher
      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 the parts.

      Click here

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) for LHD: Click here
    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) for RHD: Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR