C1391

C1391

Description
The DTC is stored if a brake fluid, internal or other leak is detected due to improper sealing in the actuator. Internal leakage is suspected if the pump motor operates frequently without braking.

C1391:

Diagnosis Procedure

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

1.CHECK FOR BRAKE FLUID LEAKS
1. Check that there is no fluid leakage in the brake line between the brake actuator and the wheel cylinder which is the cause of DTCs.
2. Check that the brake is not dragging.

NOTE:
There is no fluid leakage or dragging.

Is the inspection result normal?
YES >> GO TO 2.
NO >> Repair or replace applicable part.

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. Wait a few minutes without operating the brake pedal.
5. Check that the output value of the accumulator pressure sensor does not decrease and that the pump motor is not activated due to a decrease in accumulator pressure.

NOTE:
Accumulator pressure does not decrease and the pump motor is not activated due to a decrease in accumulator pressure.

Is the inspection result normal?
YES >> GO TO 3.
NO >> Replace brake actuator assembly.

3.RECONFIRM DTC
1. Turn the ignition switch OFF.
2. Clear the DTC.
3. Turn the ignition switch ON.
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
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