VEHICLE STABILITY CONTROL SYSTEM, Diagnostic DTC:C1246

DTC Code DTC Name
C1246 Master Cylinder Pressure Sensor Malfunction

DESCRIPTION

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

B00897ZE65
DTC No. Detection Item DTC Detection Condition Trouble Area
C1246 Master Cylinder Pressure Sensor Malfunction

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 assembly circuit

  • Master cylinder pressure sensor circuit

  • Master cylinder pressure sensor (brake actuator assembly)
DTC Detection Conditions: C1246
Vehicle Condition
Pattern 1 Pattern 2 Pattern 3
Diagnosis Condition - - - -
Malfunction Status The voltage of the sensor signal is out of range (below 0.129 V, above 3.29 V). ○ - -
An abnormality is detected in the skid control ECU internal sensor test. - ○ -
The sensor signal offset value is out of range. - - ○
Detection Time - - -
Number of Trips 1 trip 1 trip 1 trip

Tech Tips

DTC will be output when conditions for either of the patterns in the table above are met.

WIRING DIAGRAM

Refer to DTC C1249.

Click here

CAUTION / NOTICE / HINT

Note

When replacing the skid control ECU (brake actuator assembly), perform system variant learning and acceleration sensor zero point calibration.

Click here

PROCEDURE


  1. READ VALUE USING GTS (BS1 VOLTAGE VALUE)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.


      Chassis > ABS/VSC/TRC > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      BS1 Voltage Value +BS voltage value Min.: 0.00 V, Max.: 20.00 V - Changes in proportion to battery voltage

      Chassis > ABS/VSC/TRC > Data List
      Tester Display
      BS1 Voltage Value

    4. Take a note of the +BS voltage value.

      Tech Tips

      The noted +BS voltage value is used in a later step.

      Result
      Proceed to
      NEXT

    NEXT

  2. 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
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT) Click here

    OK

  3. READ VALUE USING GTS (STOP LIGHT SWITCH ASSEMBLY)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.


      Chassis > ABS/VSC/TRC > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Stop Light SW Stop light switch assembly ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

      		 -

      Chassis > ABS/VSC/TRC > Data List
      Tester Display
      Stop Light SW

    4. Check that the stop light switch assembly display observed on the GTS changes according to brake pedal operation.

      OK
      The GTS displays on or off according to brake pedal operation.
      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (STP TERMINAL) Click here

    OK

  4. READ VALUE USING GTS (MASTER CYLINDER PRESSURE SENSOR)


    1. Start the engine.

    2. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.


      Chassis > ABS/VSC/TRC > Data List
      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

      Chassis > ABS/VSC/TRC > Data List
      Tester Display
      Master Cylinder Sensor

    3. Check that the brake fluid pressure value of the master cylinder pressure sensor observed on the GTS changes when the brake pedal is depressed.

      OK
      When the brake pedal is depressed, the voltage displayed on the GTS increases.
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here

    OK

  5. RECONFIRM DTC


    1. Clear the DTCs.


      Chassis > ABS/VSC/TRC > Clear DTCs

    2. Turn the ignition switch off.

    3. Start the engine.

    4. Drive the vehicle and depress the brake pedal several times to test the stop light circuit.

    5. Check if the same DTC is output.


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      C1246 is not output A
      C1246 is output B

    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here

  6. CHECK HARNESS AND CONNECTOR (STP TERMINAL)


    1. B008807C71
      *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.

      OK
      The connector is securely connected.

    3. Disconnect the A34 skid control ECU (brake actuator assembly) connector.

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

      OK
      No deformation or corrosion.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A34-42 (STP) - Body ground Stop light switch assembly on (Brake pedal depressed) (+BS x 0.85) to 14 V*
      A34-42 (STP) - Body ground Stop light switch assembly off (Brake pedal released) Below 1.5 V

      Tech Tips

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

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)