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Home >> Lexus >> 2008 >> GX 470 >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Brake System (Service Information) >> Hydraulic Brake Booster >> On-Vehicle Inspection

On-Vehicle Inspection

  1. INSPECT BRAKE MASTER CYLINDER FLUID PRESSURE CHANGE 
    1. Inspect the battery voltage.

      Battery voltage: 

      11 to 14 V 

    2. Turn the ignition switch OFF and depress the brake pedal more than 40 times.

      HINT:

      When pressure in the power supply system is released, reaction force becomes light and stroke becomes longer.

    3. Install the LSPV gauge (SST) and brake pedal effort gauge, and bleed air.

      SST 09709-29018 

      Fig 1: Inspecting Brake Master Cylinder Fluid Pressure Change
      G05845127Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    4. When the booster does not operate:

      Depress the brake pedal and check fluid pressure.

      At 245 N (25 kgf, 55 lbf): 

      BRAKE PRESSURE CHART

      Front brake pressure Rear brake pressure
      3,150 kPa (32.1 kgf/cm2 , 457 psi) or more 0 kPa (0 kgf/cm2 , 0 psi)

      At 343 N (35 kgf, 77 lbf): 

      BRAKE PRESSURE CHART

      Front brake pressure Rear brake pressure
      4,540 kPa (46 3 kgf/cm2 , 659 psi) or more 0 kPa {0 kgf/cm2 , 0 psi)
    5. When the booster operates:

      Depress the brake pedal and check fluid pressure.

      1. Turn the ignition switch to the ON position and wait until the pump motor has stopped.
      2. Depress the brake pedal and check fluid pressure.

        At 49 N (5 kgf, 11 lbf): 

        BRAKE PRESSURE CHART

        Front brake pressure Rear brake pressure
        1,120 to 2,320 kPa (11 4 to 23.7 kgf/cm2 , 162 to 337 psi) 1,220 to 2,420 kPa (12 4 to 24.7 kgf/cm2 , 177 to 351 psi)

        At 98 N (10 kgf, 22 lbf): 

        BRAKE PRESSURE CHART

        Front brake pressure Rear brake pressure
        3,840 to 5,040 kPa (39 2 to 51 4 kgf/cm2 , 557 to 731 psi) 4,500 to 5,700 kPa (45 9 to 58 1 kgf/cm2 , 653 to 827 psi)

        At 147 N (15 kgf, 33 lbf): 

        BRAKE PRESSURE CHART

        Front brake pressure Rear brake pressure
        6,460 to 7,660 kPa (65 9 to 78 1 kgf/cm2 , 937 to 1,111 psi) 7,930 to 9,130 kPa (80 9 to 93 1 kgf/cm2 , 1,150 to 1,324 psi)

        At 196 N (20 kgf, 44 lbf): 

        BRAKE PRESSURE CHART

        Front brake pressure Rear brake pressure
        8,720 to 9,920 kPa (88 9 to 101 2 kgf/cm2 , 1,265 to 1,439 psi) 11,330 to 12,530 kPa (115 5 to 127 8 kgf/cm2 , 1,644 to 1,818 psi)
  2. INSPECT BRAKE MASTER CYLINDER OPERATION 
    1. Inspect the battery voltage.

      Battery voltage: 

      11 to 14 V 

    2. Turn the ignition switch OFF and depress the brake pedal more than 20 times.

      HINT:

      When pressure in the power supply system is released, reaction force decreases and stroke becomes longer.

    3. Check that the brake pedal reaction force decreases.

      If the pedal reaction force does not decreases, check and replace the brake line and brake master cylinder.

    4. Turn the ignition switch to the ON position and check the pump motor operation noise.

      If the pump motor does not operate, check and replace the wire harness and pump motor (See REMOVAL  ).

    5. Connect the Techstream to the DLC3.
    6. Turn the ignition switch to the ON position.
    7. Select "Active Test" mode on the Techstream.

      HINT.

      Please refer to the Techstream operator's manual for further details.

    8. Jack up and support the vehicle.
    9. Release the parking brake lever.
    10. Shift the transfer shift lever to the "N" position and check that the rear wheels rotate by hand.
    11. Inspect front VSC solenoid (SMCF) operation
      1. Select "TRAC Solenoid (SRCF)" on the Techstream.
      2. Turn the "TRAC Solenoid (SRCF)" ON with the Techstream, depress the brake pedal with stable force and check that the pedal cannot be depressed.

        If the pedal can be depressed, replace the brake master cylinder.

        NOTE: When operating it continuously, set the interval of more than 20 seconds.

        HINT:

        To protect the solenoids, the Techstream turns OFF automatically 2 sec. after every solenoid has been turned ON.

      3. Release the brake pedal.
      4. When the solenoid is OFF, depress the brake pedal again and check that the brake pedal can be depressed.

        If the pedal cannot be depressed, replace the brake master cylinder.

    12. Inspect front VSC solenoid (SREA) operation.
      1. Select "TRAC Solenoid (SRCF & SRCR)" on the Techstream.
      2. Turn the "TRAC Solenoid (SRCF & SRCR)" ON simultaneously with the Techstream, then depress the brake pedal with stable force.
      3. When the solenoids are ON, check that the front wheels do not rotate by hand.

        If the front wheels rotate, replace the brake master cylinder.

        NOTE: When operating it continuously, set the interval of more than 20 seconds.

        HINT:

        • To protect the solenoids, the Techstream turns OFF automatically 2 sec. after every solenoid has been turned ON.
        • When rotating the wheels fast, the fail-safe function is activated and judgement cannot be made properly. Rotate the wheels as slowly as possible.
      4. When the solenoids are OFF, turn the "TRAC Solenoid (SRCF)" ON again, and then depress the brake pedal. Then check the front wheels by rotating them by hand.

        If the front wheels stop, replace the brake master cylinder.

      5. When the "TRAC Solenoid (SRCF)" is OFF, depress the brake pedal again and check that the brake pedal can be depressed.

        If the pedal cannot be depressed, replace the brake master cylinder.

    13. Inspect front ABS solenoid (SFRH) operation.
      1. Select "ABS Solenoid (SFRH)" on the Techstream.
      2. Turn the "ABS Solenoid (SFRH)" ON with the Techstream, then depress the brake pedal with stable force.
      3. When the solenoid is ON, check the right front wheel by rotating it by hand.

        If the right front wheel stops, replace the brake master cylinder.

        NOTE: When operating it continuously, set the interval of more than 20 seconds.

        HINT:

        • To protect the solenoids, the Techstream turns OFF automatically 2 sec. after every solenoid has been turned ON.
        • When rotating the wheel fast, the fail-safe function is activated and judgement cannot be made properly. Rotate the wheel as slowly as possible.
      4. When the solenoid is OFF, depress the brake pedal again and check that the right front wheel does not rotate by hand.

        If the right front wheel rotates, replace the brake master cylinder.

        HINT:

        When rotating the wheel fast, the fail-safe function is activated and judgement cannot be made properly. Rotate the wheel as slowly as possible.

    14. Inspect front ABS solenoid (SFLH) operation.
      1. Select "ABS Solenoid (SFLH)11 on the Techstream.
      2. Turn the "ABS Solenoid (SFLH)" ON with the Techstream, then depress the brake pedal with stable force.
      3. When the solenoid is ON, check the left front wheel by rotating it by hand.

        If the left front wheel stops, replace the brake master cylinder.

        NOTE: When operating it continuously, set the interval of more than 20 seconds.

        HINT:

        • To protect the solenoids, the Techstream turns OFF automatically 2 sec. after every solenoid has been turned ON.
        • When rotating the wheel fast, the fail-safe function is activated and judgement cannot be made properly. Rotate the wheel as slowly as possible.
      4. When the solenoid is OFF, depress the brake pedal again and check that the left front wheel does not rotate by hand.

        If the left front wheel rotates, replace the brake master cylinder.

    15. Inspect front ABS solenoid (SFRR) operation.
      1. Select "ABS Solenoid (SFRR & SFRH)11 on the Techstream.
      2. Depress the brake pedal with stable force, then turn the "ABS Solenoid (SFRR & SFRH)" ON simultaneously with the Techstream.
      3. When the solenoids are ON, check that the right front wheel by rotating it by hand.

        If the right front wheel stops, replace the brake master cylinder.

        NOTE: When operating it continuously, set the interval of more than 20 seconds.

        HINT:

        • To protect the solenoids, the Techstream turns OFF automatically 2 sec. after every solenoid has been turned ON.
        • When rotating the wheel fast, the fail-safe function is activated and judgement cannot be made properly. Rotate the wheel as slowly as possible.
      4. When the solenoids are OFF, depress the brake pedal again and check that the right front wheel does not rotate by hand. If the right front wheel rotates, replace the brake master cylinder.
    16. Inspect front ABS solenoid (SFLR) operation.
      1. Select "ABS Solenoid (SFLR & SFLH)" on the Techstream.
      2. Depress the brake pedal with stable force, then turn the "ABS Solenoid (SFLR & SFLH)" ON simultaneously with the Techstream.
      3. When the solenoids are ON, check the left front wheel by rotating it by hand.

        If the left front wheel stops, replace the brake master cylinder.

        NOTE: When operating it continuously, set the interval of more than 20 seconds.

        HINT:

        • To protect the solenoids, the Techstream turns OFF automatically 2 sec. after every solenoid has been turned ON.
        • When rotating the wheel fast, the fail-safe function is activated and judgement cannot be made properly Rotate the wheel as slowly as possible.
      4. When the solenoids are OFF, depress the brake pedal again and check that the left front wheel does not rotate by hand.

        If the left front wheel rotates, replace the brake master cylinder.

    17. Inspect rear VSC solenoid (SREC) operation.
      1. Select "TRAC Solenoid (SRMF)" on the Techstream.
      2. Depress the brake pedal with stable force, then turn the "TRAC Solenoid (SRMF)" ON with the Techstream.
      3. Release the brake pedal when the solenoid is on, and check that the rear wheels do not rotate by hand.

        If the rear wheels rotate, replace the brake master cylinder.

        NOTE: When operating it continuously, set the interval of more than 20 seconds.

        HINT:

        • To protect the solenoids, the Techstream turns OFF automatically 2 sec. after every solenoid has been turned ON.
        • When rotating the wheels fast, the fail-safe function is activated and judgement cannot be made properly. Rotate the wheels as slowly as possible.
      4. When the solenoid is OFF, check the rear wheels by rotating them by hand. If the rear wheels stop, replace the brake master cylinder.
    18. Inspect rear VSC solenoid (STR) operation.
      1. Select "TRAC Solenoid (SRMF & SRMR)" on the Techstream.
      2. Turn the "TRAC Solenoid (SRMF & SRMR)" ON simultaneously with the Techstream.
      3. When the solenoids are ON, check that the rear wheels do not rotate by hand.

        If the rear wheels rotate, replace the brake master cylinder.

        NOTE: When operating it continuously, set the interval of more than 20 seconds.

        HINT:

        • To protect the solenoids, the Techstream turns OFF automatically 2 sec. after every solenoid has been turned ON.
        • When rotating the wheels fast, the fail-safe function is activated and judgement cannot be made properly. Rotate the wheels as slowly as possible.
      4. When the solenoids are OFF, turn the "TRAC Solenoid (SRMF)" ON again, and check the rear wheels by rotating them by hand.

        If the rear wheels stop, replace the brake master cylinder.

      5. When the "TRAC Solenoid (SRMF)" is OFF, depress the brake pedal again and check that the rear wheels do not rotate by hand.

        If the rear wheels rotate, replace the brake master cylinder.

    19. Inspect rear ABS solenoid (SRRH) operation.
      1. Select "ABS Solenoid (SRRH)11 on the Techstream.
      2. Turn the "ABS Solenoid (SRRH)" ON with the Techstream, then depress the brake pedal with stable force.
      3. When the solenoid is ON, check the right rear wheel by rotating it by hand.

        If the right rear wheel stops, replace the brake master cylinder.

        NOTE: When operating it continuously, set the interval of more than 20 seconds.

        HINT:

        • To protect the solenoids, the Techstream turns OFF automatically 2 sec. after every solenoid has been turned ON.
        • When rotating the wheel fast, the fail-safe function is activated and judgement cannot be made properly. Rotate the wheel as slowly as possible.
      4. When the solenoid is OFF, depress the brake pedal again and check that the right rear wheel does not rotate by hand.

        If the right rear wheel rotates, replace the brake master cylinder.

        HINT:

        When rotating the wheel fast, the fail-safe function is activated and judgement cannot be made properly. Rotate the wheel as slowly as possible.

    20. Inspect rear ABS solenoid (SRLH) operation.
      1. Select "ABS Solenoid (SRLH)" on the Techstream.
      2. Turn the "ABS Solenoid (SRLH)" ON with the Techstream, then depress the brake pedal with stable force.
      3. When the solenoid is ON, check the left rear wheel by rotating it by hand.

        If the left rear wheel stops, replace the brake master cylinder.

        NOTE: When operating it continuously, set the interval of more than 20 seconds.

        HINT:

        • To protect the solenoids, the Techstream turns OFF automatically 2 sec. after every solenoid has been turned ON.
        • When rotating the wheel fast, the fail-safe function is activated and judgement cannot be made properly. Rotate the wheel as slowly as possible.
      4. When the solenoid is OFF, depress the brake pedal again and check that the left rear wheel does not rotate by hand.

        If the left rear wheel rotates, replace the brake master cylinder.

    21. Inspect rear ABS solenoid (SRRR) operation.
      1. Select "ABS Solenoid (SRRR & SRRH)" on the Techstream.
      2. Depress the brake pedal with stable force, then turn the "ABS Solenoid (SRRR & SRRH)" ON simultaneously with the Techstream.
      3. When the solenoids are ON, check the right rear wheel by rotating it by hand.

        If the right rear wheel stops, replace the brake master cylinder.

        NOTE: When operating it continuously, set the interval of more than 20 seconds.

        HINT:

        • To protect the solenoids, the Techstream turns OFF automatically 2 sec. after every solenoid has been turned ON
        • When rotating the wheel too fast, the failsafe function is activated and judgement cannot be made properly. Rotate the wheel as slowly as possible.
      4. When the solenoids are OFF, depress the brake pedal again and check that the right rear wheel does not rotate by hand. If the right rear wheel rotates, replace the brake master cylinder.
    22. Inspect rear ABS solenoid (SRLR) operation.
      1. Select "ABS Solenoid (SRLR & SRLH)" on the Techstream.
      2. Depress the brake pedal with stable force, then turn the "ABS Solenoid (SRLR & SRLH)" ON simultaneously with the Techstream.
      3. When the solenoids are ON, check the left rear wheel by rotating it by hand.

        If the left rear wheel stops, replace the brake master cylinder.

        NOTE: When operating it continuously, set the interval of more than 20 seconds.

        HINT:

        • To protect the solenoids, the Techstream turns OFF automatically 2 sec. after every solenoid has been turned ON.
        • When rotating the wheel too fast, the failsafe function is activated and judgement cannot be made properly. Rotate the wheel as slowly as possible.
      4. When the solenoids are OFF, depress the brake pedal again and check that the left rear wheel does not rotate by hand.

        If the left rear wheel rotates, replace the brake master cylinder.

    23. Lower the vehicle.
    24. Disconnect the Techstream.
  3. INSPECT BRAKE FLUID LEVEL 
    1. Turn the ignition switch OFF, depress the brake pedal 20 times or more (until the pedal reaction feels light and pedal stroke becomes longer), and adjust the fluid level to the MAX level.
    2. When the ignition switch is turned to the ON position, brake fluid is sent to the accumulator and the fluid level decreases by approximately 5 mm from the level when the ignition switch is OFF (normal).
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