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 or brake booster pump. Internal leaks are suspected if the pump motor operates frequently without braking.

DTC Code 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 booster with master cylinder (Brake actuator)

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

INSPECTION PROCEDURE

Note

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

PROCEDURE


  1. CHECK FOR FLUID LEAK


    1. Check that there is no fluid leaks in the brake line between the brake actuator and the wheel cylinder which is indicated by DTCs.

    2. Check that the brake is not dragging.

      OK
      There is 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 recorded Click here.

      Result
      Result Proceed to
      DTC (C1391/69) is output A
      DTC (C1391/69) is not output (for LHD) B
      DTC (C1391/69) is not output (for RHD) C

    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER Click here

    C

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER Click here

    A

  3. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (SOLENOID VALVE)


    1. Turn the power switch off.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the power switch on (IG).

    4. Select the Active Test on the intelligent tester Click here.

      Tech Tips

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


      • ABS main relay is on.

      • Park (P) is selected.

      • Parking brake is applied.

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

      ABS/VSC/TRC
      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 intelligent tester.

    6. Select the Data List on the intelligent tester Click here.

      ABS/VSC/TRC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Wheel Cylinder Pressure Sensor Wheel cylinder pressure sensor / Min.: 0 V, Max.: 5 V When brake pedal released: 0.1 to 0.9 V Reading increases when brake pedal is depressed

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

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

      Tech Tips

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

      Result
      Result Proceed to
      The output value of the wheel cylinder increases A
      The output values of the wheel cylinders do not increase B

    B

    REPLACE BRAKE BOOSTER PUMP Click here

    A

  4. REPLACE BRAKE BOOSTER WITH MASTER CYLINDER


    1. Replace the brake booster with master cylinder (brake actuator) Click here for LHD or Click here for RHD).


    NEXT

    REPLACE BRAKE BOOSTER PUMP Click here