DTC C1246: Master Cylinder Pressure Sensor Malfunction; DTC C1281: Master Cylinder Pressure Sensor Output Malfunction (Test Mode DTC) [08/2013 - 12/2013]: Procedure

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 → See step   10 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Start the engine.
3. Select the Data List using the Techstream. Refer to DATA LIST / ACTIVE TEST [08/2013 - ] .
   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 → See step   11 

OK: Go to next step 

1. Select the Data List using the Techstream. Refer to DATA LIST / ACTIVE TEST [08/2013 - ] .
   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 → See step   5 

C → See step   6 

D → See step   8 

A: Go to next step 

1. Turn the ignition switch off.
2. Clear the DTCs. Refer to DTC CHECK / CLEAR [08/2013 - ] .
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. Refer to DTC CHECK / CLEAR [08/2013 - ] .

   Result

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

B → See step   11 

A → See step   9 

1. Turn the ignition switch off.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   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 → See step   11 

1. Turn the ignition switch off.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   TEXT IN ILLUSTRATION
   
   

   *a	Component without harness connected (Brake Pedal Load Sensing Switch (Brake Pedal Support Assembly))

NG → See step   12 

OK: Go to next step 

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 → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   11 

1. Turn the ignition switch off.
2. Check the brake pedal height and stop light switch assembly installation. Refer to ADJUSTMENT [08/2013 - ] .

   OK

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

NG → See step   13 

OK → See step   12