I have a 2004 Avalanche 1500 5.3L V8 4x4 Z71 with tow Package my brake lines were rusted replaced all the lines to the ABS module bleed the lines but only getting pressure in one cylinder & power is going to the motor module is the modulator clogged or need to be replaced when bleeding the lines there was very little fluid coming out of them & tried to go in by computer to have the pump bleed the lines it blocked me out ? what is causing this problem to not get equal pressure to my wheel cylinders!