C1246

BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: C1246, C1281: Master Cylinder Pressure Sensor Malfunction
C1281 - Master Cylinder Pressure Sensor Output Malfunction (Test Mode DTC)

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.









WIRING DIAGRAM

Refer to DTCs C1249 and C1429 C1249 and C1429).

INSPECTION PROCEDURE

PROCEDURE

1. CHECK STOP LIGHT OPERATION

(a) Check that the stop lights come on when the brake pedal is depressed, and go off when the brake pedal is released.

OK:





NG -- INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT) Problem Symptoms Table
OK -- Continue to next step.

2. READ VALUE USING TECHSTREAM (MASTER CYLINDER PRESSURE SENSOR)

(a) Connect the Techstream to the DLC3.

(b) Start the engine.

(c) Select the Data List using the Techstream Data List / Active Test.

ABS/VSC/TRAC





(d) 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 -- REPLACE BRAKE ACTUATOR ASSEMBLY Removal
OK -- Continue to next step.

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

(a) Select the Data List using the Techstream Data List / Active Test.

ABS/VSC/TRAC





(b) 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.

(c) 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:





B -- CHECK HARNESS AND CONNECTOR (STP TERMINAL)

C -- CHECK BRAKE PEDAL LOAD SENSING SWITCH

D -- CHECK BRAKE PEDAL AND STOP LIGHT SWITCH ASSEMBLY INSTALLATION
A -- Continue to next step.

4. RECONFIRM DTC

(a) Turn the ignition switch off.

(b) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.

(c) Turn the ignition switch off.

(d) Start the engine.

(e) 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).

(f) Check if the same DTC is output Reading and Clearing Diagnostic Trouble Codes.

Result:





B -- REPLACE BRAKE ACTUATOR ASSEMBLY Removal

A -- CHECK FOR INTERMITTENT PROBLEMS How To Proceed With Troubleshooting

5. CHECK HARNESS AND CONNECTOR (STP TERMINAL)

(a) Turn the ignition switch off.





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

(c) Disconnect the skid control ECU connector.

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

Standard Voltage:





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





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

OK -- REPLACE BRAKE ACTUATOR ASSEMBLY Removal

6. CHECK BRAKE PEDAL LOAD SENSING SWITCH

(a) Turn the ignition switch off.





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

(c) Disconnect the brake pedal load sensing switch connector.

NOTICE:
* 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.

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

Standard Resistance:





Text in Illustration





NG -- REPLACE BRAKE PEDAL SUPPORT ASSEMBLY Removal
OK -- Continue to next step.

7. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BRAKE PEDAL LOAD SENSING SWITCH)

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

(b) Disconnect the skid control ECU connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE BRAKE ACTUATOR ASSEMBLY Removal

8. CHECK BRAKE PEDAL AND STOP LIGHT SWITCH ASSEMBLY INSTALLATION

(a) Turn the ignition switch off.

(b) Check the brake pedal height and stop light switch assembly installation Adjustments.

OK:

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

NG -- ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH ASSEMBLY Adjustments

OK -- REPLACE BRAKE PEDAL SUPPORT ASSEMBLY Removal