Sonny Blair

I have a 2002 Cadillac Escalade AWD and sometimes when I'm making a turn, ie: turning into a parking space or entering a freeway on ramp my steering tries to lock up! My stabilitrak and brake light are lite up on my screen. I took it to my mechanic, he put his tester on it and the code said it was my Electronic Brake Control Module (this part has been discontinued by the dealer) He found one in a junk yard (cost $500.00) and installed it. The brake lite on the dash went out but the stabilitrak light is still on and my steering still locks up occasionally. When I took it back and he tested it again, the code said the brakes need bleeding, he bled them several times and it continues to say they need to be bled! What could be causing this?