VEHICLE STABILITY CONTROL SYSTEM, Diagnostic DTC:C1246/46, C1281/81

DTC Code DTC Name
C1246/46 Master Cylinder Pressure Sensor Malfunction
C1281/81 Master Cylinder Pressure Sensor Output Malfunction (Test Mode DTC)

DESCRIPTION

The master cylinder pressure sensor is built into the brake actuator assembly.

DTC C1281/81 will be deleted when the master cylinder pressure sensor sends a master cylinder pressure signal or when Test Mode ends. DTC C1281/81 is output only in Test Mode.

DTC Code DTC Detection Condition Trouble Area
C1246/46

Any of the following is detected:


  1. At a vehicle speed of 7 km/h (4.3 mph) or more, when the PMC terminal voltage is over 0.86 V, it does not change by 0.005 V or more for 30 seconds.

  2. Noise occurs in the PMC terminal 7 times or more within 5 seconds.

  3. When the stop light switch is OFF, the PMC terminal voltage is more than 0.86 V or less than 0.3 V for 5 seconds or more.

  4. With the IG1 terminal voltage between 9.5 and 18.5 V, the VCM terminal voltage is not between 4.4 and 5.6 V for 1.2 seconds or more.

  5. When the VCM terminal voltage between 4.4 and 5.6 V, the PMC terminal voltage is not between 0.19 and 4.57 V for 1.2 seconds or more.

  • Master cylinder pressure sensor

  • Master cylinder pressure sensor circuit

  • Stop light switch circuit

  • Skid control ECU
C1281/81 Detected only during Test Mode.

  • Stop light switch

  • Brake pedal load sensing switch

  • Master cylinder pressure sensor

WIRING DIAGRAM

A01637ME03

INSPECTION PROCEDURE

Note

When replacing the skid control ECU, perform zero point calibration and store system information Click here.

PROCEDURE


  1. CHECK STOP LIGHT OPERATION


    1. Check that the stop light comes on when the brake pedal is depressed, and goes off when the brake pedal is released.

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

    NG

    INSPECT STOP LIGHT CIRCUIT Click here

    OK

  2. READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH AND BRAKE PEDAL LOAD SENSING SWITCH)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Select the Data List mode on the intelligent tester Click here.

      ABS/VSC/TRC
      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 the specified point

      OFF: Brake pedal not depressed beyond the specified point

      		 -

    4. Check that the stop light switch display and brake pedal load sensing switch display observed on the intelligent tester change according to brake pedal operation.

      OK
      The intelligent tester displays ON or OFF according to brake pedal operation.

    5. Slowly depress the brake pedal, and check when the stop light switch and brake pedal load sensing switch turn ON.

      OK
      The stop light switch should turn ON first, 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 (The brake pedal load sensing switch turns on first) C

    B

    INSPECT SKID CONTROL ECU (STP1 TERMINAL) Click here

    C

    CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION Click here

    A

  3. READ VALUE USING INTELLIGENT TESTER (MASTER CYLINDER PRESSURE SENSOR)


    1. Select the Data List mode on the intelligent tester Click here.

      ABS/VSC/TRC
      Tester Display Measurement Item / Range Normal Condition Diagnostic Note
      Master Cylinder Sensor Master cylinder pressure sensor / min.: 0 V, max.: 5 V When brake pedal is released: 0.3 to 0.9 V Reading increases when brake pedal is depressed

    2. Check that the brake fluid pressure value of the master cylinder pressure sensor observed on the intelligent tester changes when the brake pedal is depressed.

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

    NG

    CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BRAKE ACTUATOR) Click here

    OK

  4. RECONFIRM DTC


    1. Turn the engine switch off.

    2. Clear the DTCs Click here.

    3. Start the engine.

    4. Drive the vehicle at a speed of 30 km/h (18 mph) or more and perform braking test (decelerate the vehicle by depressing the brake pedal).

    5. Check if the same DTC is recorded Click here.

      Result
      Result Proceed to
      DTC (C1246/46) is not output A
      DTC (C1246/46) is output B

    B

    REPLACE SKID CONTROL ECU Click here

    A

    CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) Click here

  5. INSPECT SKID CONTROL ECU (STP1 TERMINAL)


    1. A0163E5E07

      Turn the engine 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 Switch Condition Specified Condition
      J77-10 (STP1) - Body ground Stop light switch ON (Brake pedal depressed) 8 to 14 V
      J77-10 (STP1) - Body ground Stop light switch OFF (Brake pedal released) Below 1.5 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STP1 CIRCUIT)

    OK

    REPLACE SKID CONTROL ECU Click here

  6. CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION


    1. Turn the engine switch off.

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

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

    NG

    ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH Click here

    OK

    REPLACE BRAKE PEDAL SUPPORT ASSEMBLY (BRAKE PEDAL LOAD SENSING SWITCH) Click here

  7. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BRAKE ACTUATOR)


    1. A01626RE09

      Turn the engine switch off.

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

    3. Disconnect the skid control ECU connector and the brake actuator connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      J78-18 (VCM) - A13-20 (VCM) Always Below 1 Ω
      J78-18 (VCM) - Body ground Always 10 kΩ or higher
      J78-4 (PMC) - A13-17 (PMC) Always Below 1 Ω
      J78-4 (PMC) - Body ground Always 10 kΩ or higher
      J78-6 (E2) - A13-19 (E2) Always Below 1 Ω
      J78-6 (E2) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. INSPECT SKID CONTROL ECU (SENSOR INPUT)


    1. A015ZJ2E07

      Reconnect the skid control ECU connector and the brake actuator connector.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      J78-18 (VCM) - Body ground Engine switch on (IG) 4.5 to 5.5 V

    NG

    REPLACE SKID CONTROL ECU Click here

    OK

  9. INSPECT SKID CONTROL ECU (SENSOR OUTPUT)


    1. A015ZJ2E08

      Remove either the right or left front brake cylinder bleeder plug.

    2. Install the pressure gauge via the attachment, and bleed the gauge of air Click here.

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

      Standard Voltage
      Tester Connection

      Fluid Pressure

      MPa (kgf/cm2, psi)

      		 Specified Condition
      J78-4 (PMC) - Body ground 0 (0, 0) 0.37 to 0.63 V
      J78-4 (PMC) - Body ground 5.88 (60, 853) 1.57 to 1.83 V
      J78-4 (PMC) - Body ground 11.8 (120, 1707) 2.77 to 3.03 V

    NG

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    OK

    REPLACE SKID CONTROL ECU Click here