ELECTRONICALLY CONTROLLED BRAKE SYSTEM Abnormal Brake Pedal Response on First Depression

DESCRIPTION

If the vehicle has been stopped without opening or closing the driver door for a long period of time, the electronically controlled brake system will not be ready and sufficient fluid pressure may not be stored in the accumulator. In this case, the brake pedal response may not be the same as usual the first time the brake pedal is depressed. This is not a malfunction.

WIRING DIAGRAM

Figure 1. for RHD:

B000WMBE02
*a Front Door Courtesy Light Switch Assembly RH
*b Skid Control ECU Assembly

Figure 2. for LHD:

B000WMBE01
*a Front Door Courtesy Light Switch Assembly LH
*b Skid Control ECU Assembly

CAUTION / NOTICE / HINT

Note

When replacing the skid control ECU assembly, perform initialization and calibration of the linear solenoid valve.

Click here

PROCEDURE


  1. BRAKE PROBLEM CHECK


    1. Check the conditions at the time the problem occurred.


      1. Whether a warning light illuminated or the buzzer sounded.

      2. The number of times the engine switch was turned on (IG) since the latest symptom occurred.

      3. Frequency of the symptom.

      Result
      Proceed to
      NEXT

    NEXT

  2. CHECK DTC


    1. Clear the DTCs.

      Click here


      Chassis > ABS/VSC/TRC > Clear DTCs

    2. Turn the engine switch off.

    3. Turn the engine switch on (IG).

    4. Check the DTCs (electronically controlled brake system) that are output.

      Click here


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      DTCs C1391 and C1256 are not output. A
      DTCs C1391 and/or C1256 are output. B

    B

    REPAIR CIRCUITS INDICATED BY OUTPUT DTCS Click here

    A

  3. CHECK VEHICLE


    1. Turn the engine switch off.

    2. Depress the brake pedal within 2 minutes of opening the driver door and check the response of the brake pedal.

    3. Release the brake pedal and wait for 2 minutes without depressing the brake pedal, opening or closing the driver door or operating the engine switch.

    4. After 2 seconds or more have elapsed, depress the brake pedal and check that the first depression response is different to successive depression responses.

      Tech Tips

      Compare the response of the brake pedal when the system is in sleep mode and when the stroke simulator is operating.

      Result
      Result Proceed to
      The response of the brake pedal does not change. A
      The response of the brake pedal changed. B

    B

    END

    A

  4. INSPECT COURTESY LIGHT SWITC


    1. Set the interior light door switch to ON and check that the map light assembly illuminates, then set the interior light door switch to DOOR.

    2. Check that the map light assembly illuminates when the driver door is opened.

      OK
      The map light assembly illuminates when the driver door is opened.
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT LIGHTING SYSTEM (COURTESY LIGHT SWITCH CIRCUIT) Click here

    OK

  5. CHECK HARNESS AND CONNECTOR (CTY TERMINAL)


    1. B000YVCC08
      *a

      Component with harness connected

      (Skid Control ECU Assembly)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A8-14 (CTY) - Body ground Driver door open Below 1 V
      A8-14 (CTY) - Body ground Driver door closed Pulse generation (waveform 1)

      1. B000YV4C02
        *a Driver door closed
        *b Driver door open

        Waveform 1 (Reference)

        Item Content
        Tester Connection A8-14 (CTY) - Body ground
        Tool Setting 5 V/DIV., 10 ms./DIV.
        Vehicle Condition Driver door closed → open
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE SKID CONTROL ECU ASSEMBLY for RHD: Click here
    REPLACE SKID CONTROL ECU ASSEMBLY for LHD: Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (CTY CIRCUIT)