Bleeding ABS Pump

[Larry Herman]

Terry, I do not have a diagram of the internal workings of the ABS module, but from talking to one guy I know who is familiar with it, the unit has valves in it which cycle rapidly, momentarily relieving the pressure on the brake caliper piston. The normal flow of fluid is right past the "front side" of these valves. Air can become trapped behind these valves, and the regular bleeding process will not purge it. The valves must be cycled as you bleed in order to get the trapped air out.