Mark, it should probably be noted that Workhorse split up the auto parking brake system in 2001, mounting the pump and green switch up front under the hood, and the gray switch, associated plumbing and actuator in a metal box near where the entry door is commonly located. Prior to then the pump assembly was mounted in the same box. The OP lists this as a 2001 coach, which may be built on either a 2000 or 2001 chassis, so either setup may apply.
p.s. it also appears the OP is wanting to complain about the problem, and not give us specific information to help solve it, which is fine. Unless that changes I am done with this thread.