Depressurizing Hydraulic Accumulator

Early Production Model
The pump/motor assembly charges the hydraulic accumulator to a pressure between approximately 2100 and 2600 psi (14,480 and 17,930 kPa) anytime that the ignition is in the "ON" position. The pump/motor assembly does not operate under the following conditions:
- Ignition OFF
- Either battery cable disconnected
- Sensor block connector disconnected from the hydraulic unit

Unless otherwise specified, the hydraulic accumulator should be depressurized before disassembling any portion of the hydraulic system. Follow the procedure below to depressurize the hydraulic accumulator:
1. With ignition off, sensor block connector disconnected from hydraulic assembly, or negative battery cable disconnected, pump the brake pedal a minimum of 25 times, using approximately 50 lb. (222 N) pedal force. A noticeable change in pedal feel will occur when the accumulator is discharged.
2. When a definite increase in pedal effort is felt, stroke pedal a few additional times. This should remove all hydraulic pressure from the system.



Late Production Model
The Anti-lock Brake System (ABS) pump/motor assembly charges the hydraulic accumulator to a pressure between 1600-2000 psi anytime the ignition is in the ON position. The pump/motor cannot run if the ignition is OFF or either battery cable is disconnected.

The hydraulic accumulator should be depressurized before disassembling any portion of the hydraulic system.
1. Turn ignition switch to the OFF position, or disconnect battery ground cable.
2. Pump brake pedal a minimum of 40 times using approximately 50 pounds of pedal force. Pedal feel should change noticeably when accumulator is discharged.
3. After a definite increase in pedal effort is felt, pump pedal a few additional times. This will remove all hydraulic pressure from the system.