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HOMESERVICE MANUALSPONTIAC1990GRAND PRIX STE, 3.1 VREPAIR AND DIAGNOSISBRAKESTRACTION CONTROLANTI-LOCK BRAKE SYSTEMDIAGNOSIS & TESTINGABS-III FUNCTION CHECK "D": PUMP-RUN TIME EXCESSIVE
1990 Pontiac Grand Prix STE, 3.1 V

Abs-III Function Check "D": Pump-Run Time Excessive

1990 Pontiac Grand Prix STE, 3.1 VSECTION Abs-III Function Check "D": Pump-Run Time Excessive
  1. Turn ignition off. Disengage pump wire harness connector. Turn ignition on. Connect Digital Volt-Ohmmeter (DVOM) positive lead to pin "A" (White wire). Connect negative DVOM lead to ground and measure voltage. If voltage is less than 12 volts, check battery, charging system and related circuitry.
  2. If voltage is greater than 12 volts, turn ignition off. Connect pump wire harness connector and depressurize system. With ignition off, pump brake pedal a MINIMUM of 40 times with complete pedal strokes. Remove accumulator and install Pressure Gauge (J-37118). Attach accumulator on pressure gauge. Bleed Powermaster-III at bleeder valves. Turn ignition on while observing pressure gauge.
  3. System pressure should quickly rise from zero to 500 psi (35 kg/cm2 ). If system pressure does not rise quickly, replace accumulator. Turn ignition on to charge system. Observe maximum system pressure. If system pressure is more than 2900 psi (204 kg/cm2 ), replace pressure switch.
  4. Observe pump activity with scanner while applying brake pedal 3 times. Record low-pressure reading when pump is turned on. Motor should come on at 2000 psi (141 kg/cm2 ) or higher. If motor does not come on at specified pressure, replace pressure switch.
    CAUTION: DO NOT apply brakes with reservoir cover removed.
  5. If pressure switch is okay, check pump inlet in reservoir assembly for restriction. Turn ignition on with engine off. If inlet is clear, place clear plastic hose over relief valve in reservoir. See Figure.
  6. Hold other end of tube (downward) in reservoir rear chamber. If fluid flows through tube into reservoir, replace relief valve. If fluid does not flow through tube, place one end of clear plastic tube over booster return port. See Figure.
  7. Place other end of tube (pointing downward) in rear reservoir. Turn ignition on. If fluid flows through tube, replace Powermaster-III unit. If no fluid flows, replace pump and motor.
RENDER: 1.0x

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.