we are having an issue with the air brakes on our 2011 mru613, foot brake and hand brake work as they should how ever the parking brake valve is set but brakes are released. push the button and it wont stay in. again the parking brake button is in the SET position but brakes are NOT set button will not stay in when pressed. any ideas? ive already replaced the button valve thinking it could be bad, also the pressure protection valve on the in dash manifold is constantly leaking air after it reaches 60/80 psi.
