GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 Yukon Denali 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Accumulator Leak-Down Test
  1. Start the engine.
  2. Charge the accumulator by pressing the brake pedal or by completely turning the steering wheel in one direction and then in the other.
  3. Turn the engine off. Let the vehicle sit for an hour.
  4. Perform two power assisted applications with the engine off.
  5. If the accumulator failed to hold a charge after one hour, but functions normally after charging, the accumulator valves are malfunctioning. Replace the accumulator. Refer to Hydraulic Brake Booster Accumulator Replacement .
  6. If the charging and discharging of the accumulator is audible, but the accumulator still fails to hold a charge, the accumulator valves are malfunctioning. Replace the accumulator. Refer to Hydraulic Brake Booster Accumulator Replacement .
  7. Empty the accumulator by pressing the brake pedal 30 times.
  8. The accumulator can will rotate or wobble if the accumulator has lost its gas charge. This replace the accumulator. Refer to Hydraulic Brake Booster Accumulator Replacement .