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Home >> Subaru >> 2017 >> WRX Base >> Repair and Diagnosis (Single Page) >> Brakes >> Traction Control >> Vehicle Dynamics Control (VDC) System (Service Information) >> VDC Control Module and Hydraulic Control Unit (VDC Control Module & H/U) >> Inspection >> Checking The Hydraulic Unit Abs Operation By Pressure Gauge

Checking The Hydraulic Unit Abs Operation By Pressure Gauge

  1. Lift up the vehicle, and then remove the wheel.
  2. Remove the bleeder - screws from the front LH and front RH caliper bodies.
  3. Connect two pressure gauges to front LH and front RH caliper bodies.
    CAUTION:
    • Use a pressure gauge used exclusively for brake fluid measurement.
    • Do not use the pressure gauge used for the measurement of transmission oil. Doing so will cause the piston seal to expand and deform.
    NOTE: Wrap sealing tape around the pressure gauge.
    Fig 1: Checking Hydraulic Unit VDC Operation Using Pressure Gauge
    G08314724Courtesy of SUBARU OF AMERICA, INC.
  4. Bleed air from the pressure gauges and the front LH and front RH caliper bodies.
  5. Perform ABS sequence control. <Ref. to ABS SEQUENCE CONTROL .>
    NOTE: When the hydraulic unit begins to work, first the front LH side performs decompression, hold and compression, and then the front RH side performs decompression, hold and compression.
  6. Read values indicated on the pressure gauge and check if the fluctuation of the values between decompression and compression meets the standard values. Depress the brake pedal and check that the kick-back is normal, and tightness is normal.
    Inspection conditions Front wheel Rear wheel
    Initial value 3, 500 kPa (36 kgf/cm2 , 511 psi) 3, 500 kPa (36 kgf/cm2 , 511 psi)
    When depressurized 500 kPa (5 kgf/cm2 , 73 psi) or less 500 kPa (5 kgf/cm2 , 73 psi) or less
    When pressurized 3, 500 kPa (36 kgf/cm2 , 511 psi) or more 3, 500 kPa (36 kgf/cm2 , 511 psi) or more
  7. Remove the pressure gauge from the front LH and front RH caliper bodies.
  8. Install the bleeder - screws of the front LH and front RH caliper bodies.
  9. Remove the bleeder - screws from the rear LH and rear RH caliper bodies.
  10. Connect two pressure gauges to rear LH and rear RH caliper bodies.
  11. Bleed air from the pressure gauges and the rear LH and rear RH caliper bodies.
  12. Perform ABS sequence control. <Ref. to ABS SEQUENCE CONTROL .>
    NOTE: When the hydraulic unit begins to work, first the rear LH side performs decompression, hold and compression, and then the rear RH side performs decompression, hold and compression.
  13. Read values indicated on the pressure gauge and check if the fluctuation of the values between decompression and compression meets specification. Depress the brake pedal and check that the kick-back is normal, and tightness is normal.
  14. Remove the pressure gauge from the rear LH and rear RH caliper bodies.
  15. Install the bleeder - screws of the rear LH and rear RH caliper bodies.
  16. Bleed air from the brake system. <Ref. to Air Bleeding .>
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