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Home >> Lexus >> 2021 >> LC 500 2D Coupe >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Electronically Controlled Brake System - Diagnostic Codes (Coupe) (3 Of 4) >> Electronically Controlled Brake System >> DTC C1391/69: Accumulator Leak Malfunction [03/2017 - 09/2018] >> Procedure

DTC C1391/69: Accumulator Leak Malfunction [03/2017 - 09/2018]: Procedure

  1. RECONFIRM DTC 
    1. Start the engine.
    2. Check if the same DTC is output.

      Refer to DTC CHECK / CLEAR [03/2017 - 09/2018]

      Chassis > ABS/VSC/TRAC > Trouble Codes 

      Result

      Result Proceed to
      DTC C1365/54 is not output. A
      DTC C1365/54 is output. B

    Result: 

    B 

    GO TO DTC (C1365/54). Refer to  DTC C1365/54: Accumulator Pressure Sensor Malfunction [03/2017 - 09/2018]  

    Result: 

    A 

    See step  2

  2. CHECK FOR FLUID LEAK 
    1. Check that there are no fluid leaks in the brake lines between the brake booster with accumulator pump assembly and the brake actuator assembly.
    2. Check that there are no fluid leaks in the brake lines between the brake actuator assembly and the wheel cylinders.
    3. Check that the brakes are not dragging.

      OK

      There are no fluid leaks or dragging.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE APPLICABLE PART 

    Result: 

    OK 

    See step  3

  3. READ VALUE USING TECHSTREAM (ACCUMULATOR PRESSURE SENSOR) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Select the Data List on the Techstream.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023]

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Accumulator Sensor Accumulator pressure sensor Min.: 0.00 V, Max.: 5.00 V Specified value: 2.60 to 3.80 V When brake fluid is stored in the accumulator: Accumulator pressure changes in accordance with volume of fluid stored in the accumulator

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display
      Accumulator Sensor
    4. Depress the brake pedal 4 or 5 times and operate the pump motor.
    5. Wait for 30 seconds without depressing the brake pedal.
    6. Check that the accumulator pressure sensor output value change is within the specified range.

      OK

      Accumulator pressure sensor output value change is less than 0.20 V.

      HINT: 

      • This inspection is performed to determine if a long-term power malfunction occurred when low pressure is detected due to a defective sensor, an internal leak in the brake actuator assembly, or deterioration of the accumulator.
      • External brake fluid leaks are suspected if the fluid level drops inside the brake master cylinder reservoir assembly.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    NG 

    See step  4

  4. PERFORM ACTIVE TEST USING TECHSTREAM (SOLENOID VALVE) 
    1. Turn the engine switch off.
    2. Connect the Techstream to the DLC3.
    3. Turn the engine switch on (IG).
    4. Select the Active Test on the Techstream.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023]

    5. With the brake pedal released, set "ECB Solenoid (SMC1)" to "ON" and check the output voltage of "FR W/C Sensor".
      1. ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      ECB Solenoid (SMC1) Master cut solenoid (SMC1) Solenoid ON/OFF ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      FR W/C Sensor Front wheel cylinder pressure sensor RH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed

      Chassis > ABS/VSC/TRAC > Active Test 

      Active Test Display
      ECB Solenoid (SMC1)
      Data List Display
      FR W/C Sensor
      1. ECB: Electronically Controlled Brake System

      OK

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

      HINT: 

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

      Result

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

    Result: 

    B 

    See step  8

    Result: 

    A 

    See step  5

  5. PERFORM ACTIVE TEST USING TECHSTREAM (SOLENOID VALVE) 
    1. Turn the engine switch off.
    2. Connect the Techstream to the DLC3.
    3. Turn the engine switch on (IG).
    4. Select the Active Test on the Techstream.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023]

    5. With the brake pedal released, set "ECB Solenoid (SMC2)" to "ON" and check the output voltage of "FL W/C Sensor".
      1. ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      ECB Solenoid (SMC2) Master cut solenoid (SMC2) Solenoid ON/OFF ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      FL W/C Sensor Front wheel cylinder pressure sensor LH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed

      Chassis > ABS/VSC/TRAC > Active Test 

      Active Test Display
      ECB Solenoid (SMC2)
      Data List Display
      FL W/C Sensor
      1. ECB: Electronically Controlled Brake System

      OK

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

      HINT: 

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

      Result

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

    Result: 

    B 

    See step  8

    Result: 

    A 

    See step  6

  6. PERFORM ACTIVE TEST USING TECHSTREAM (SOLENOID VALVE) 
    1. Turn the engine switch off.
    2. Connect the Techstream to the DLC3.
    3. Turn the engine switch on (IG).
    4. Select the Active Test on the Techstream.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023]

    5. With the brake pedal released, set the current of "ECB Solenoid (SLRRR)" to 1.2 A and check the output voltage of "RR W/C Sensor".
      1. ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      ECB Solenoid (SLRRR) Linear solenoid (RRR) valve Solenoid ON/OFF ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      RR W/C Sensor Rear wheel cylinder pressure sensor RH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed

      Chassis > ABS/VSC/TRAC > Active Test 

      Active Test Display
      ECB Solenoid (SLRRR)
      Data List Display
      RR W/C Sensor
      1. ECB: Electronically Controlled Brake System

      OK

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

      HINT: 

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

      Result

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

    Result: 

    B 

    See step  8

    Result: 

    A 

    See step  7

  7. PERFORM ACTIVE TEST USING TECHSTREAM (SOLENOID VALVE) 
    1. Turn the engine switch off.
    2. Connect the Techstream to the DLC3.
    3. Turn the engine switch on (IG).
    4. Select the Active Test on the Techstream.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023]

    5. With the brake pedal released, set the current of "ECB Solenoid (SLRRL)" to 1.2 A and check the output voltage of "RL W/C Sensor".
      1. ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      ECB Solenoid (SLRRL) Linear solenoid (RLR) valve Solenoid ON/OFF ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      RL W/C Sensor Rear wheel cylinder pressure sensor LH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed

      Chassis > ABS/VSC/TRAC > Active Test 

      Active Test Display
      ECB Solenoid (SLRRL)
      Data List Display
      RL W/C Sensor
      1. ECB: Electronically Controlled Brake System

      OK

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

      HINT: 

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

      Result

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

    Result: 

    A 

    REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    B 

    See step  8

  8. REPLACE BRAKE ACTUATOR ASSEMBLY 
    1. Replace the brake actuator assembly.

      Refer to REMOVAL [03/2017 - 05/2023]

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY 

    Refer to REMOVAL [03/2017 - 05/2023]

    HINT: 

    The load on the brake booster pump with accumulator assembly is increased due to fluid leaking inside the brake actuator assembly. The performance of the brake booster pump with accumulator assembly may decrease. Therefore, replace the brake booster pump with accumulator assembly at the same time.

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