C1256

C1256

Description
The accumulator pressure sensor is built into the actuator and detects the accumulator pressure.

The brake ECU turns on the brake warning lamp and sounds the brake warning buzzer if it senses a decrease in the accumulator pressure.

C1256:

Diagnosis Procedure

CAUTION:
When replacing the brake ECU or brake actuator assembly, perform initialization of linear solenoid valve and calibration.

NOTE:
When C1241, C1252 or C1253 is output together with C1256, inspect and repair the trouble areas indicated by C1241, C1252 or C1253 first.

1.BRAKE PROBLEM CHECK
Ask the customer if frequent braking is performed when the brake control warning lamp comes on.





NOTE:
This DTC is output even if the accumulator pressure drops only temporarily due to frequent braking.

A >> GO TO 2.
B >> INSPECTION END

2.READ VALUE OF CONSULT-III (ACCUMULATOR PRESSURE SENSOR)
1. Connect the CONSULT-III.
2. Turn the ignition switch ON.
3. Select the "DATA MONITOR" on the CONSULT-III.

ABS/VDC:

4. Depress the brake pedal 4 or 5 times to operate the pump motor, and check the output value on the CONSULT-III with the motor stopped (not braking).

NOTE:
Accumulator pressure sensor's output voltage does not drop.

Is the inspection result normal?
YES >> GO TO 3.
NO >> GO TO 4.

3.INSPECT BRAKE ACTUATOR ASSEMBLY
1. Turn the ignition switch OFF.
2. Disconnect the brake actuator connector.
3. Measure the resistance according to the value(s) in the table below.





Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace brake actuator assembly.

4.RECONFIRM DTC
1. Reconnect the brake actuator connector.
2. Clear the DTC.
3. Perform the road and braking test.
4. Check if the same DTC is recorded.

Result:

A >> Check for intermittent problems (symptom simulation).
B >> Replace brake ECU.

Special Repair Requirement

1.ZERO ADJUSTMENT FOR EACH SENSOR AND OFFSET LEANING FOR LINEAR SOLENOID VALVE
After erasing brake ECU memories, perform zero adjustment of following sensors and initialization of linear solenoid valve.
^ Steering angle sensor: BRC-9, "PERFORM ZERO POINT OF STEERING ANGLE SENSOR: Description". Testing and Inspection
^ Yaw rate/side/decel G sensor: BRC-8, "PERFORM ZERO POINT OF YAW RATE/SIDE/DECEL G SENSOR: Description". Testing and Inspection
^ Brake stroke sensor: BRC-9, "PERFORM ADJUSTMENT OF STROKE SENSOR: Description". Perform Adjustment of Stroke Sensor
^ Linear solenoid valve: BRC-7, "PERFORM INITIALIZATION OF LINEAR SOLENOID VALVE AND CALIBRATION: Description". Perform Initialization of Linear Solenoid Valve and Calibration
>> END