[alltrac]

When a caliper piston is pushed in, brake fluid gets forced backward, up into the system. Since the caliper is the lowest point in the system, dirt and corrosion naturally accumulate in this area. When grime and dirt find their way into the HCU portion of the ABS system, both can cause valves to stick, which leads to a vehicle pulling one way or another; accumulators to stick open, which leads to low pedal; compensator ports to plug, which leads to dragging brakes; and of course, it can make the ABS light come on leading to all of the above. If installers get in the habit of opening the bleeder when they compress the caliper piston, as well as selling customers a brake fluid flush, these problems will more than likely not occur