A couple of days ago the Parking Brake warning light refused to go off and that was accompanied by a very audible air hiss from the rear of the coach. To make a long story short we eventually had the problem diagnosed and had to have the air chamber (actuator) replaced. On Patriot's and Thunders the parking brake is a air actuated caliper that functions on a rotor attached to the drive shaft.
Normally, no one thinks about whether your parking brake pads have worn out. For us, however, this is the second time. After we bought the coach a service center had found that the parking brake pads had worn to the metal and I chalked it off to the previous owner having driven it without releasing the brake. Now I realize that it is quite likely that the actuator has been leaking for a while, probably even prior to our ownership. This time one of the brake pads had worn through the pad and the steel backing plate as if it had been dragging, at least occasionally, for quite some time. Our MH has always "used" more air than "normal" while driving, but no one has ever been able to find a leak. What I think has been happening is that air has been been leaking out of the air chamber through the rubber seal around the actuator stud. As long as the air leak was slow and intermittent the air compressor could handle it without issue. When the coach was parked there was no unusual air loss because the brake was depressurized.
After a day of driving I have convinced myself that the coach now uses significantly less air than before; the compressor runs noticeably less often.
I'm passing this along in case someone else encounters this sort of issue. The air chamber is a ~$650 part at BCS. Getting to it to replace it and the pads is not a fun job.
