VEHICLE STABILITY CONTROL SYSTEM, Diagnostic DTC:C1246, C1281

DTC Code DTC Name
C1246 Master Cylinder Pressure Sensor Malfunction
C1281 Master Cylinder Pressure Sensor Output Malfunction (Test Mode DTC)

DESCRIPTION

The master cylinder pressure sensor is connected to the skid control ECU in the brake actuator assembly.

DTC C1281 is cleared when the Lost Booster Pressure Judgment Check is performed correctly in Test Mode and the check indicates a pass, or when Test Mode ends. DTC C1281 is output only in Test Mode.

A01HPFEE33
DTC No. DTC Detection Condition Trouble Area
C1246

Any of the following is detected:


  1. The voltage of the sensor signal is out of range (below 0.129 V, above 3.29 V).

  2. An abnormality is detected in the skid control ECU internal sensor test.

  3. The sensor signal offset value is out of range.


  • Stop light switch circuit

  • Master cylinder pressure sensor circuit

  • Master cylinder pressure sensor (Brake actuator assembly)

C1281 Detected only during Test Mode.
  • Stop light switch assembly

  • Brake pedal load sensing switch (Brake pedal support assembly)

  • Brake booster assembly

  • Master cylinder pressure sensor (Brake actuator assembly)

WIRING DIAGRAM

Refer to DTCs C1249 and C1429 Click here and Click here.

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK STOP LIGHT OPERATION


    1. Check that the stop lights come on when the brake pedal is depressed, and go off when the brake pedal is released.

      OK
      Condition Illumination Condition
      Brake pedal depressed. ON
      Brake pedal released. OFF

    NG
    OK
  2. READ VALUE USING TECHSTREAM (MASTER CYLINDER PRESSURE SENSOR)


    1. Connect the Techstream to the DLC3.

    2. Start the engine.

    3. Select the Data List using the Techstream Click here.

      ABS/VSC/TRAC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Master Cylinder Sensor Master cylinder pressure sensor reading / Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.20 to 0.40 V Reading increases when brake pedal is depressed
    4. Check that the brake fluid pressure value of the master cylinder pressure sensor observed on the Techstream changes when the brake pedal is depressed.

      OK
      When the pedal is depressed, the voltage displayed on the Techstream increases.

    NG
    OK
  3. READ VALUE USING TECHSTREAM (STOP LIGHT SWITCH ASSEMBLY AND BRAKE PEDAL LOAD SENSING SWITCH)


    1. Select the Data List using the Techstream Click here.

      ABS/VSC/TRAC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light SW Stop light switch / ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

      -
      Brake Pedal Load Sensing SW Brake pedal load sensing switch / ON or OFF

      ON: Brake pedal depressed beyond a specified point

      OFF: Brake pedal not depressed beyond a specified point

      -
    2. Check that the stop light switch display and brake pedal load sensing switch display observed on the Techstream change according to brake pedal operation.

      OK
      The Techstream displays on or off according to brake pedal operation.
    3. Slowly depress the brake pedal, and check when the stop light switch and brake pedal load sensing switch turn on.

      OK
      First the stop light switch should turn ON, and then the brake pedal load sensing switch should turn ON.
      Result
      Result Proceed to
      OK A
      NG (The stop light switch does not turn on.) B
      NG (Turning on of the brake pedal load sensing switch is not confirmed.) C
      NG (The brake pedal load sensing switch turns on first.) D

    B
    C
    D
    A
  4. RECONFIRM DTC


    1. Turn the ignition switch off.

    2. Clear the DTCs Click here.

    3. Turn the ignition switch off.

    4. Start the engine.

    5. At a speed of 30 km/h (18 mph) or more, drive the vehicle and perform a braking test (decelerate the vehicle by depressing the brake pedal).

    6. Check if the same DTC is output Click here.

      Result
      Result Proceed to
      DTC C1246 is not output. A
      DTC C1246 is output. B

    B
    A
  5. CHECK HARNESS AND CONNECTOR (STP TERMINAL)


    1. A01HP27E06
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

      Turn the ignition switch off.

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

    3. Disconnect the skid control ECU connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A49-30 (STP) - Body ground Stop light switch ON (Brake pedal depressed) 11 to 14 V*
      A49-30 (STP) - Body ground Stop light switch OFF (Brake pedal released) Below 1.5 V

      Tech Tips

      *: The standard voltage value varies depending on the +BS terminal voltage value. The standard voltage is 85% of the +BS terminal voltage.


    NG
    OK
  6. CHECK BRAKE PEDAL LOAD SENSING SWITCH


    1. A01HQR6E01
      Text in Illustration
      *a

      Component without harness connected

      (Brake Pedal Load Sensing Switch (Brake Pedal Support Assembly))

      Turn the ignition switch off.

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

    3. Disconnect the brake pedal load sensing switch connector.

      Note


      • Do not remove the brake pedal load sensing switch from the brake pedal support assembly.

      • When there is a malfunction in the brake pedal load sensing switch, replace the brake pedal support assembly.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      2 (FSW+) - 1 (FSW-)

      Switch OFF

      (Brake pedal depressed)

      950 to 1050 Ω
      2 (FSW+) - 1 (FSW-)

      Switch ON

      (Brake pedal released)

      203 to 223 Ω

    NG
    OK
  7. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BRAKE PEDAL LOAD SENSING SWITCH)


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

    2. Disconnect the skid control ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A49-34 (FSW+) - A40-2 (FSW+) Always Below 1 Ω
      A49-34 (FSW+) - Body ground Always 10 kΩ or higher
      A40-1 (FSW-) - Body ground Always Below 1 Ω

    NG
    OK
  8. CHECK BRAKE PEDAL AND STOP LIGHT SWITCH ASSEMBLY INSTALLATION


    1. Turn the ignition switch off.

    2. Check the brake pedal height and stop light switch assembly installation Click here.

      OK
      The brake pedal height and stop light switch assembly installation are normal.

    NG
    OK