From my IC Dealer for those who have these systems; 1) Be sure to make sure you have a good ground for the HCU to Frame. A bad ground would result in the pump motor trying to ground back within its self. The best ground would be to remove the four nuts from the outside of the frame and clean the area to make sure you have a good ground to frame.
2) Over filling the Master Cylinder has been an issue. Make sure to check the brake fluid level when the system is totally discharged and not charged. The best way to discharge the system is to remove the two 30 amp maxifuses and then apply the brake pedal a minimum of 30 times.
3) Make sure brake fluid doesn’t over flow to where it runs out of the cap. Should this happen, the cap must then be replaced. I have found that several shops will try to drill a hole in the cap due to the vent become clogged when brake fluid has reached the cap. This isn’t the way to correct the problem. The cap must be replaced.
4) Brake fluid is hydroscopic (Which means it absorbs moisture) and must be flushed every two years due to the boiling point lowers to where when the brakes get hot, the fluid expands so much that the brakes will apply on their own causing brake drag.
5) When replacing the parking brake cable, make sure you install it proper. There is a “Hash Mark” on the cable that must be line up with the nose of the SAHR Canister.