What would cause the power steering and the power brakes to fail on a chevy avalanch

Question edited for all the typos and translated into written English.
Question moved to model category.

https://www.google.com/search?q=2004+Chevy+Avalanche.+My+brake+pedal+is+locked

You have a vacuume line that has failed probably in the engine compartment. Look for a hole in a line or a line off . If you cant find a line off you r brake power booster may have gone bad. if this was helpful please leave good feed back

It would appear that your vehicle has a Hydroboost system (many Chevys do), which uses hydraulic pressure from the power steering pump to also boost the brakes. Check your power steer fluid level. If it is OK, then either you have air in the system, or the pump is failing. Also check all the hoses and pipes between the pump and brake master cylinder for leakage.

was the electric brake control module professionaly installed? first check the ground behind the module and make sure it doesnt share the same one as your heater. too much current on a poor ground can cause both circuits to quit working.

YOUR VECHICLE HAS THE HYDRALIC BOOSTER.WHICH YOU POWER STEERING PUMP CONTROL BRAKING SYSTEM.CHECK POWER STEERING PUMP FLIUD LEVEL.IF LOW CHECK POWER STEERING PUMP HOSES FOR LEAKS.IF YOU FIND NO LEAKS.THE HYDRALIC BOOSTER OR POWER STEERING PUMP FAULTY.

Hoses from pump to steering box. Orings on these hoses!

check for a blown power steering line, lack of fluid in the power steering reservoir, and check to see if the pump is blown. i believe the brake boost on this truck is assisted by the pressure and flow of the power steering pump. also check for leaks on steering gear box

Hello altgraph1: My name is Roger and I can help. The power steering and the brakes are directly connected. If the power steering pump fails you will also loose the brake assist. This vehicle does not have a vacuum booster you have a hydro-boost brake system. This unit uses the power steering pressure to assist the stopping of the vehicle. You will need special tools to determine if the power steering pump failed or if the hydro-boost system failed. Most likely the power steering pump failed. How ever to be sure it should be tested first. Should you need further help please just ask. Please rate the answer you received. Thank You for using Fix Ya. Roger

Check to see if the power steering reservoir is full and the belt is intact.I'm assuming that you have a hydroboost unit where the p/s works the brake booster. If those are ok you could have a bad p/s pump