DTC C1281: Master Cylinder Pressure Sensor Output Malfunction (Test Mode DTC): 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   11 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Select the Data List on the Techstream. Refer to DATA LIST / ACTIVE TEST .
   DATA LIST
   
   

   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 Techstream change according to brake pedal operation.

   OK

   The Techstream 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

   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 (Turning on of the stop light switch is not confirmed)	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

D → See step   7 

C → See step   6 

B → See step   5 

A: Go to next step 

1. Select the Data List on the Techstream. Refer to DATA LIST / ACTIVE TEST .
   DATA LIST
   
   

   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 Techstream changes when the brake pedal is depressed.

   OK

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

NG → See step   9 

OK: Go to next step 

1. Turn the engine switch off.
2. Perform the sensor check in the Test Mode procedure. Refer to TEST MODE PROCEDURE .

   OK

   All Test Mode DTCs are cleared.

NG → See step   9 

OK → See step   8 

1. Turn the engine switch off.
   Fig 1: Identifying Connector Terminals

   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	Switch Condition	Specified Condition
   A58-2 (STP1) - Body ground	Stop light switch ON (Brake pedal depressed)	8 to 14 V
   A58-2 (STP1) - Body ground	Stop light switch OFF (Brake pedal released)	Below 1.5 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STP1 CIRCUIT) 

OK → See step   9 

1. Turn the engine switch off.
   Fig 2: Identifying Connector Terminals

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

   Standard Resistance

   Tester Connection	Switch Condition	Specified Condition
   A58-27 (FSW+) - Body ground	Brake pedal load sensing switch OFF (Brake pedal depressed)	0.9 to 1.1 kΩ
   A58-27 (FSW+) - Body ground	Brake pedal load sensing switch ON (Brake pedal released)	192 to 234 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (FSW+ CIRCUIT) 

OK → See step   9 

1. Turn the engine switch off.
2. Check the brake pedal height and stop light switch installation. Refer to ADJUSTMENT .

   OK

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

NG → See step   12 

OK → See step   10