I didn't have the same problems as you are having, but I wanted to throw in my 2 cents about Pacbrake and Harold's customer service. When I installed mine I had some issues with the brake working intermittently. The problem ended up being a bad crimp connection at the main power wire and a bad solenoid. Harold was very patient over numerous phone calls and e-mails and twice sent me new parts at no cost to sort out my issues. Brake has been working great over the past 15,000 km. I'll never drive another diesel truck without an exhaust brake. I've only every used the Pacbrake PRXB, so I have no other brake to compare it to, but I highly recommend it.
Ron