I have a 2002 Safari Trek which is on the P32 Chassis and is very similar to yours, with the exception that the Automatic parking brake pump is moved to just under the drivers left foot so I easily hear it every time it engages (on yours the pump should be mounted next to the actuator under the frame, there is a reservoir mounted by the pump with fluid you need to check). The only time it makes noise is when I shift out of park, there is no sound from the pump when shifting from R to N to D. Having said that I would get the linkage looked at as soon as possible,I know of people who have lost their motorhomes to fires caused by a dragging automatic parking brake.