DTC    C1246    Master Cylinder Pressure Sensor Malfunction

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

for Preparation Click here


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.

C106656E33


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.
  1. Stop light switch circuit
  2. Master cylinder pressure sensor circuit
  3. Master cylinder pressure sensor (Brake actuator assembly)
C1281
Detected only during Test Mode.
  1. Stop light switch assembly
  2. Brake pedal load sensing switch (Brake pedal support assembly)
  3. Brake booster assembly
  4. Master cylinder pressure sensor (Brake actuator assembly)

WIRING DIAGRAM

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

INSPECTION 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
INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT) (Click here)
OK


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

  1. Connect the intelligent tester to the DLC3.

  1. Start the engine.

  1. Select the Data List using the intelligent tester (Click here).

    ABS/VSC/TRC 
    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

  1. 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, the voltage displayed on the intelligent tester increases.


NG
REPLACE BRAKE ACTUATOR ASSEMBLY (Click here)
OK


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

  1. Select the Data List using 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 a specified point
    OFF: Brake pedal not depressed beyond a specified point
    		-

  1. 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.

  1. 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
Go to step 5

C
Go to step 6

D
Go to step 8
A


4.RECONFIRM DTC

  1. Turn the ignition switch off.

  1. Clear the DTCs (Click here).

  1. Turn the ignition switch off.

  1. Start the engine.

  1. 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).

  1. 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
REPLACE BRAKE ACTUATOR ASSEMBLY (Click here)
A

CHECK FOR INTERMITTENT PROBLEMS (Click here)  

5.CHECK HARNESS AND CONNECTOR (STP TERMINAL)


    C238832E13

  1. Turn the ignition switch off.

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

  1. Disconnect the skid control ECU connector.

  1. 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

    HINT:
    *: The standard voltage value varies depending on the +BS terminal voltage value. The standard voltage is 85% of the +BS terminal voltage.
    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to Skid Control ECU (Brake Actuator Assembly))


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)
OK

REPLACE BRAKE ACTUATOR ASSEMBLY (Click here)  

6.INSPECT BRAKE PEDAL LOAD SENSING SWITCH


    C239141E01

  1. Turn the ignition switch off.

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

  1. Disconnect the brake pedal load sensing switch connector.

    NOTICE:
    1. Do not remove the brake pedal load sensing switch from the brake pedal support assembly.
    2. When there is a malfunction in the brake pedal load sensing switch, replace the brake pedal support assembly.

  1. 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
    Text in Illustration 
    *a
    		Component without harness connected
    (Brake Pedal Load Sensing Switch (Brake Pedal Support Assembly))

    Result:

    Result
    		Proceed to
    OK
    		A
    NG (for LHD)
    		B
    NG (for RHD)
    		C


B
REPLACE BRAKE PEDAL SUPPORT ASSEMBLY (Click here)

C
REPLACE BRAKE PEDAL SUPPORT ASSEMBLY (Click here)
A


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.

  1. Disconnect the skid control ECU connector.

  1. 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
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE BRAKE ACTUATOR ASSEMBLY (Click here)  

8.CHECK BRAKE PEDAL AND STOP LIGHT SWITCH ASSEMBLY INSTALLATION

  1. Turn the ignition switch off.

  1. Check the brake pedal height and stop light switch assembly installation (Click here for LHD or Click here for RHD).

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

    Result:

    Result
    		Proceed to
    OK (for LHD)
    		A
    OK (for RHD)
    		B
    NG (for LHD)
    		C
    NG (for RHD)
    		D


B
REPLACE BRAKE PEDAL SUPPORT ASSEMBLY (Click here)

C
ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH ASSEMBLY (Click here)

D
ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH ASSEMBLY (Click here)
A

REPLACE BRAKE PEDAL SUPPORT ASSEMBLY (Click here)