I replaced the master cylinder in my 1993 Buick LeSabre. As one drives and depresses the brake pedal the brakes engage and will not release. For some reason the fluid does not seem to be getting back into the master cylinder even though the brake pedal is released. The car's brakes were on so hard I could not drive it. By opening the brake lines at the mater cylinder and releasing some brake fluid the brakes de-energized and I could then drive the car. Any Thoughts? Thanks Joe

Question edited for clarity. Wrong break/brake, and wrong peddle/pedal.

Replace the cable. It will be the same as the LeSabre

https://www.google.com/search?q=2005+Buick+Park+Avenue+replace+parking+brake+cable

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Step on brake pedal and see if you have brake lights. The brake light switch release the solenoid to let it shift. If brakes lights work then the solenoid could be defective. Also the fuses should be checked for the brake lights if they don't work.

I would say the brake Master Cylinder is worn out. Check inside all the wheels for signs of brake fluid also. You might have a blown brake line or hose.

Any auto parts outlet will carry replacement brake lines and connectors.Not costly either,except for the connectors,their brass.I replace all brake lines every time I build another vehicle in this manner.After all lines are replaced,go to the brake bleeder farthest from the master cylinder and take it out.Fill the master cylinder,and the brake will bleed themselves with gravity.omce fluid comes out of the farthest,close it off .Then,Go to the closest to m-cylinder,having someone push the brake pedal to bleed it out and so forth for the others.Rigger

I would jack up a front wheel and see if pushing on the pedal with the engine running will stop the wheel from turning.
You need to know if the pressure is reaching the wheels, or if the pads and rotors are too slick to stop the car.
Usually if the pedal is hard, the booster is not working or the brakes are glazed.
Can you stop the car with the parking brake ? That only uses the rear brakes.
You may need a second opinion from a different shop.

1. Check the fluid level in the reservoir after bleeding each wheel. Add DOT3 fluid, if necessary.
2. If the master cylinder was disassembled or if the reservoir becomes empty, bleed the air from the master cylinder as follows:
   1. Disconnect the brake lines from the master cylinder.
   2. Slowly depress the brake pedal and hold it.
   3. Block off the outlet plug with your finger, and release the brake pedal.
   4. Repeat 3 or 4 times.
   
   
3. Bleed the brake starting with the one furthest from the reservoir and then the next furthest, etc.
   
4. Depress the brake pedal several times, then loosen the bleeder plug with the pedal held down.
5. At the point when fluid stops coming out, tighten the bleeder plug to 11 Nm (8 ft. lbs.), then release the brake pedal.
6. Repeat until all the air in the fluid has been bled out.
7. Repeat the procedure to bleed the air out of brake line for each wheel.
8. Check the fluid level and add DOT3 fluid if necessary.

make sure fluid full lid on.open bleed screw put finger over hole in end of bleeder,have someone slowly pump break pedal whule finger still on bleeder.8/10 times.should start to get fluid.top master up.open bleeder depress pedal slowly close bleeder while pedal down.release pedal and repeat.if system ran dry few more steps lrt me know.

if you can see a good amount of wet brake fluid between the brake master cylinder and the brake booster. and you have been adding fliud often,you could have a bad master cylinder. it has to be replaced not rebuilt. you however may have a far more common problem, a rusted through brake line.have someone pump the brake pedal, than look under the car for a brake fluid leak ,repair as needed. than bleed the brakes for a good hard brake pedal
good luck chris

Sounds like a bad master cylinder. Possibly a bad power booster with the leak you are describing. Check for leaks in lines/hoses/wheel cylinders as well.

still got air bleed more