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

A001RSLE07

CAUTION / NOTICE / HINT

Note


  • After replacing the skid control ECU (brake booster with master cylinder assembly), perform linear solenoid valve offset learning, ABS holding solenoid valve learning, yaw rate and acceleration sensor zero point calibration and system information memorization after performing "Reset Memory".

    Click here

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

  • Before performing this procedure, depress the brake pedal and confirm that the stop lights illuminate.

PROCEDURE


  1. PRE-CHECK


    1. Check that all of the following conditions required for the brake warning light / red (malfunction) to turn off are met:


      1. The brake warning light / yellow (minor malfunction) and ABS warning light are not illuminated.

        Tech Tips

        If the brake warning light / yellow (minor malfunction) or ABS warning light remains illuminated, make sure that the conditions required for the brake warning light / yellow (minor malfunction) and ABS warning light to turn off are met.

      2. The brake fluid level in the brake master cylinder reservoir assembly (brake booster with master cylinder assembly) is not low.

      Result
      Proceed to
      NEXT

    NEXT

  2. 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

  3. 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

  4. 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

  5. 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

  6. CHECK HARNESS AND CONNECTOR (IG1 TERMINAL)


    1. A005NB5C91
      *a

      Front view of wire harness connector

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

      Turn the power switch off.

    2. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK
      The connector is securely connected.

    3. Disconnect the A39 skid control ECU (brake booster with master cylinder assembly) connector.

    4. Check both the connector case and the terminals for deformation and corrosion.

      OK
      No deformation or corrosion.

    5. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A39-23 (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

  7. CHECK HARNESS AND CONNECTOR (GND TERMINAL)


    1. A001RR7C92
      *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
      A39-26 (GND1) - Body ground Always Below 1 Ω
      A39-39 (GND2) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

    OK

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


    1. Reconnect the A39 skid control ECU (brake booster with master cylinder assembly) connector.

    2. 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

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

      Result
      Result Proceed to
      ON is displayed. (for LHD) A
      ON is displayed. (for RHD) B
      OFF is displayed. C

    A

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

    C

    INSPECT METER / GAUGE SYSTEM Click here