GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1997 🢒 GMC P62 Commercial Chassis 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Accumulator Leak-Down Test
  1. Start the engine.
  2. Charge the accumulator by applying the brake pedal or by turning the steering wheel from stop to stop.
  3. Turn the engine off.
  4. Let the vehicle sit for 1 hour.
  5. With the engine off, verify that at least two power-assisted applications are possible.
  6. If the accumulator will not hold a charge for 1 hour, but functions normally after being charged, replace the accumulator valves. Refer to the Light Duty Truck Unit Repair Manual.
  7. If the accumulator can be heard charging and discharging, but it does not hold a charge, replace the accumulator valves. Refer to the Light Duty Truck Unit Repair Manual.
  8. Empty the accumulator by applying the brake pedal several times.
  9. If the accumulator has lost its charge of gas, the accumulator can rotate or wobble. If this happens, replace the accumulator assembly.