Vehicle Stability Control System

BRAKE CONTROL: VEHICLE STABILITY CONTROL SYSTEM: C1246/46, C1281/81, C1449/46: Master Cylinder Pressure Sensor Malfunction


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.





WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
When replacing the skid control ECU, perform zero point calibration and store system information Vehicle Stability Control System.

PROCEDURE

1. CHECK STOP LIGHT OPERATION

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

OK:





NG -- INSPECT STOP LIGHT CIRCUIT Symptom Related Diagnostic Procedures
OK -- Continue to next step.

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

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

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

ABS / VSC / TRAC





(d) 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.

(e) 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:





C -- CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION

B -- INSPECT SKID CONTROL ECU (STP TERMINAL)
A -- Continue to next step.

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

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

ABS / VSC / TRAC





(b) 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 -- CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BRAKE ACTUATOR)
OK -- Continue to next step.

4. RECONFIRM DTC

(a) Turn the engine switch off.

(b) Clear the DTCs Vehicle Stability Control System.

(c) Start the engine.

(d) 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).

(e) Check if the same DTC is recorded Vehicle Stability Control System.

Result:





B -- REPLACE SKID CONTROL ECU Removal

A -- CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) Diagnosis System

5. INSPECT SKID CONTROL ECU (STP TERMINAL)

(a) Turn the engine 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:





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

OK -- REPLACE SKID CONTROL ECU Removal

6. CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION

(a) Turn the engine switch off.

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

OK:

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

NG -- ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH Adjustments

OK -- REPLACE BRAKE PEDAL SUPPORT ASSEMBLY (BRAKE PEDAL LOAD SENSING SWITCH) Removal

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

(a) Turn the engine switch off.





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

(c) Disconnect the skid control ECU connector and the brake actuator connector.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

8. INSPECT SKID CONTROL ECU (SENSOR INPUT)

(a) Reconnect the skid control ECU connector and the brake actuator connector.





(b) Turn the engine switch on (IG).

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

Standard voltage:





NG -- REPLACE SKID CONTROL ECU Removal
OK -- Continue to next step.

9. INSPECT SKID CONTROL ECU (SENSOR OUTPUT)

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





(b) Install a pressure gauge via the attachment, and bleed the gauge of air Service and Repair.

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

Standard voltage:





NG -- REPLACE BRAKE ACTUATOR ASSEMBLY Removal

OK -- REPLACE SKID CONTROL ECU Removal