ANTI-LOCK BRAKE SYSTEM, Diagnostic DTC:C1256

DTC Code DTC Name
C1256 Accumulator Low Pressure

DESCRIPTION

Refer to DTC C1254 Click here.

DTC Code DTC Detection Condition Trouble Area
C1256 The fluid pressure inside the accumulator is below the standard value.

  • Brake booster with accumulator pump assembly

  • Master cylinder solenoid (Accumulator pressure sensor)

  • Hydraulic brake booster assembly

CAUTION / NOTICE / HINT

Note

After replacing the master cylinder solenoid, perform zero point calibration Click here.

Tech Tips

When DTC C1251, C1253 or C1254 is output together with DTC C1256 inspect and repair the trouble area indicated by DTC C1251, C1253 or C1254 first.

PROCEDURE


  1. RECONFIRM DTC


    1. Clear the DTCs Click here.

    2. Turn the ignition switch off.

    3. Depress the brake pedal 20 times or more.

    4. Turn the ignition switch to ON.

    5. Wait for 99 seconds.

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

      Result
      Result Proceed to
      DTC is output A
      DTC is not output B

      Tech Tips

      Excessive brake pedal operation results in abnormal accumulator pressure consumption. This is normal.


    B

    CHECK FOR INTERMITTENT PROBLEMS Click here

    A

  2. INSPECT HYDRAULIC BRAKE BOOSTER ASSEMBLY FUNCTION


    1. Inspect brake booster pump power supply system function.


      1. Turn the ignition switch off.

      2. Depress the brake pedal 20 times or more to release the pressure in the accumulator.

        Tech Tips

        When the pressure is released, the brake pedal stroke becomes longer.

      3. Check that the brake fluid level is at the MAX level.

      4. Chock the 4 wheels and release the parking brake.

      5. Turn the ignition switch to ON and measure the brake booster pump operating time (the time from when the brake booster pump starts operating until it stops).

        OK
        20 to 80 seconds

      6. Start the engine after the brake boost pump stops.

      7. Check that the ABS warning light and slip indicator light are not illuminated.

      8. Turn off the engine, and then turn the ignition switch to ON.

      9. Check that the brake boost pump operates and then stops when the brake pedal is depressed 4 or 5 times.

      10. Depress the brake pedal 4 or 5 times and measure the brake booster pump operating time (the time from when the brake booster pump starts operating until it stops).

        OK
        2 to 11 seconds

      11. Check that the brake warning light illuminates and the buzzer sounds when the brake pedal is fully depressed continuously 15 to 20 times.

        Note

        Wait 120 seconds or more after turning the ignition switch to ON before performing this inspection.

    2. Check brake booster operation.


      1. Turn the ignition switch off.

      2. Depress the brake pedal 20 times or more to release the pressure in the accumulator.

        Tech Tips

        When the pressure is released, the brake pedal stroke becomes longer.

      3. Depress the brake pedal, start the engine, and check the change in the brake pedal height.

        OK
        The brake pedal moves slightly inward.

    3. Inspect brake master cylinder fluid pressure change (for LHD: See page , for RHD: Click here.


    NG

    INSPECT BRAKE BOOSTER PUMP ASSEMBLY Click here

    OK

  3. READ VALUE USING GTS (ACCUMULATOR SENSOR)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.

      ABS/VSC/TRC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Accumulator Sensor Accumulator pressure sensor reading/ Min.: 0.00 V, Max.: 5.00 V 3.58 to 5 V If the value is constant regardless of the pump operation, an accumulator pressure sensor malfunction is suspected.

    5. Check that the accumulator output value is normal.

      OK
      Accumulator pressure sensor value is normal.
      Result
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

    B

    REPLACE MASTER CYLINDER SOLENOID Click here

    C

    REPLACE MASTER CYLINDER SOLENOID Click here

    A

  4. RECONFIRM DTC


    1. Clear the DTCs Click here.

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

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

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

    B

    REPLACE MASTER CYLINDER SOLENOID Click here

    C

    REPLACE MASTER CYLINDER SOLENOID Click here

  5. INSPECT BRAKE BOOSTER PUMP ASSEMBLY


    1. Remove the hydraulic brake booster assembly (for LHD: See page , for RHD: Click here.

    2. Using a screwdriver, remove the 2 screws and pull out the wire harness from the master cylinder solenoid.

    3. B001YZWE11
      Text in Illustration
      *1 Pump motor wire harness
      *a Red wire
      *b Black wire

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Red wire terminal - Black wire terminal Always Below 2 Ω

    4. Install the pump motor wire harness to the master cylinder solenoid with the 2 screws (for LHD: See page , for RHD: Click here.

      Result
      Result Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG (for LHD) C
      NG (for RHD) D

    A

    REPLACE HYDRAULIC BRAKE BOOSTER ASSEMBLY Click here

    B

    REPLACE HYDRAULIC BRAKE BOOSTER ASSEMBLY Click here

    C

    REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY Click here

    D

    REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY Click here