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Home >> Lexus >> 2008 >> LS 460L >> Repair and Diagnosis >> Brakes >> Traction Control >> Brake Control >> Electronically Controlled Brake System >> DTC C1391/69 Accumulator Leak Malfunction >> Inspection Procedure

Inspection Procedure

NOTE: When replacing the skid control ECU or brake actuator, perform initialization of linear solenoid valve and calibration (see INITIALIZATION  ).
  1. CHECK BRAKE FLUID LEAKAGE 
    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.
      Fig 1: Identifying Brake Booster Pump And Brake Actuator
      G04949613Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Check that the brake is not dragging.

      OK: There is no fluid leakage or dragging. 

    NG: REPAIR OR REPLACE APPLICABLE PART 

    OK: Go to Next Step 

  2. CHECK DTC 
    1. Clear the DTC (see DTC CHECK / CLEAR  ).
    2. Turn the engine switch OFF.
    3. Turn the engine switch ON (IG).
    4. Check if the same DTC C1391 is recorded.

      Result 

      RESULT CHART

      Result Proceed To
      DTC C1391 is output A
      DTC C1391 is not output B

    B: REPLACE BRAKE ACTUATOR  (See REMOVAL  )

    A: Go to Next Step 

  3. PERFORM ACTIVE TEST BY TECHSTREAM (SMC1, SMC2, SLRRR, AND SLRRL) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch ON (IG).
    3. Turn the Techstream main switch on.
    4. Select the Active Test mode on the Techstream.

      HINT:

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

      • Main relay 1 and 2 are on.
      • Shift lever is P position.
      • Parking brake is on.
      • Vehicle speed is 0 km/h (0 mph).

        ABS/VSC/TRAC 

        ABS/VSC/TRAC REFERENCE CHART

        Tester Display Test Part Control Range Diagnostic Note
        Electronically Controlled Brake System Solenoid (SMC1) Turns electronically controlled brake system solenoid (SMC1) ON / OFF Operation sound of solenoid (clicking sound) can be heard
        Electronically Controlled Brake System Solenoid (SMC2) Turns electronically controlled brake system solenoid (SMC2) ON / OFF Operation sound of solenoid (clicking sound) can be heard
        Electronically Controlled Brake System Solenoid (SLRRR) Valve Close Turns SLRRR solenoid ON / OFF Operation sound of solenoid (clicking sound) can be heard
        Electronically Controlled Brake System Solenoid (SLRRL) Valve Close Turns SLRRL solenoid ON / OFF Operation sound of solenoid (clicking sound) can be heard
    5. Using the Techstream, turn SMC1, SMC2, SLRRR, or SLRRL ON.
      Fig 2: Brake Actuator Inner Diagram
      G05774022Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    6. Check that each wheel cylinder's output value does not increase.

      OK: Each wheel cylinder's output value does not increase. 

      HINT:

      If any of wheel cylinder's output value increases, there may be a brake fluid leak in the brake actuator.

      Result 

      RESULT CHART

      Result Proceed To
      Any of wheel cylinder's output value increases. A
      Each wheel cylinder's output value does not increase. B

    B: REPLACE BRAKE ACCUMULATOR PUMP  (See REMOVAL  )

    A: Go to Next Step 

  4. REPLACE BRAKE ACTUATOR 

    Replace the brake actuator (see REMOVAL  ).

    NEXT: REPLACE BRAKE ACCUMULATOR PUMP  (See REMOVAL  )

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