ELECTRONICALLY CONTROLLED BRAKE SYSTEM, Diagnostic DTC:C1391/69

DTC Code DTC Name
C1391/69 Accumulator Leak Malfunction

DESCRIPTION

The DTC is stored if internal or external brake fluid leaks are detected due to improper sealing in the brake actuator (brake booster with master cylinder assembly) or brake booster pump assembly. Internal leaks are suspected if the pump motor operates frequently without braking.

DTC No. INF Code DTC Detection Condition Trouble Area
C1391/69 351

Either of the following is detected:

  1. Accumulator pressure sensor input does not increase before braking or while the pump motor is operating.

  2. Accumulator pressure sensor input reduction rate exceeds the specification before braking and while the pump motor is not operating.

  • Brake fluid leaks

  • Brake actuator (Brake booster with master cylinder assembly)

    (Malfunctioning internal seal, low gas pressure in accumulator, etc.)

INSPECTION PROCEDURE

Note

When replacing the brake actuator (brake booster with master cylinder assembly), perform initialization and calibration of the linear solenoid valve Click here.

PROCEDURE

  1. CHECK FOR FLUID LEAK

    1. Check that there are no fluid leaks in the brake lines between the brake actuator (brake booster with master cylinder assembly) and the wheel cylinders.

    2. Check that the brakes are not dragging.

      OK
      There are no fluid leaks or dragging.
    NG

    REPAIR OR REPLACE APPLICABLE PART

    OK

  2. RECONFIRM DTC

    1. Clear the DTCs Click here.

    2. Turn the power switch on (READY).

    3. Check if the same DTC is output Click here.

      Result
      Result Proceed to
      DTC C1391/69 is output. A
      DTC C1391/69 is not output. B
    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

    A

  3. PERFORM ACTIVE TEST USING TECHSTREAM (SOLENOID VALVE)

    1. Turn the power switch off.

    2. Connect the Techstream to the DLC3.

    3. Turn the power switch on (IG).

    4. Select the Active Test on the Techstream Click here.

      Tech Tips

      The Active Test can be performed when the following conditions are met.

      • ABS main relay is on.

      • Shift lever is in P.

      • Parking brake is applied.

      • Vehicle speed is 0 km/h (0 mph).

      ABS/VSC/TRAC
      Tester Display Test Part Control Range Diagnostic Note
      ECB* Solenoid (SMC/SRC/SCC) Switching solenoid valve (SMC/SRC/SCC) Solenoid ON/OFF Operation sound of solenoid (clicking sound) can be heard

      *: Electronically Controlled Brake System

    5. Perform the Active Test of the solenoid using the Techstream.

    6. Select the Data List on the Techstream Click here.

      ABS/VSC/TRAC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Wheel Cylinder Pressure Sensor Wheel cylinder pressure sensor / Min.: 0.00 V, Max.: 5.00 V When brake pedal released: 0.10 to 0.90 V Reading increases when brake pedal is depressed

    7. Check that the output value of the wheel cylinder pressure sensor does not increase.

      OK
      The output value of the wheel cylinder pressure sensor does not increase.

      Tech Tips

      If the output value increases, there may be brake fluid leaks in the brake actuator.

      Result
      Result Proceed to
      The output value of the wheel cylinder pressure sensor increases. A
      The output values of the wheel cylinder pressure sensor does not increase. B
    B

    REPLACE BRAKE BOOSTER PUMP ASSEMBLY Click here

    A

  4. REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

    1. Replace the brake actuator (brake booster with master cylinder assembly) Click here.

    NEXT

    REPLACE BRAKE BOOSTER PUMP ASSEMBLY Click here