Is your parking brake indictor light staying on or turning off at some point after releasing the park brake? If it turns off, then first guess is moisture got in during pressure washing and there is a stuck shoe. If that is the case do a forum search on the keywords brake won't release. That should bring up some threads with good advise on getting them unstuck.If the indicator stays on and you're sure the release valve is working (listen carefully for the air), then maybe there was a brake system interlock with another system that got disconnected during your cleaning work. For example on my RTS, there is an interlock with the door controls.