Pusher Axle operation Question

Steerable pusher axles will not track going backwards so are plumbed to raise with the trans going into reverse.
Many are plumbed to raise when parking brakes are on to put more weight on parking brake axles.
The regulator is mostly plumbed after the control valves that are controlled by the reverse light and the parking brake, and the dash switch may be hooked to one or the other as an over-ride to stop air exhaust during maneuvering in reverse.

 

I think I got it unless I have missed something which is also possible. After studying the way this apparatus works, it is seeming to be highly possible they have installed a normally closed pressure switch on the park brake valve instead of a normally open, since the bag module valve defaults to a raised position with no voltage applied. This is provided there are two paths of voltage, one from the brake switch and the other through the dash switch since with the brake knob pushed in, no voltage axle raises, then you can press down switch and will have voltage applied and axle will go down. It does not seem that reverse is used as an input since it is having no affect on the operation in any fashion at present and the axle isn't steerable.
It is also coincidental that the two pressure gauges read the same pressures. This is a tad troubling since the pressure gauge at the regulator is simply to observe and allow for adjustment to the pressure being supplied to the pilot port on the air valve module. This in turn supplies load bag pressure of which is monitored on the dash gauge via a line from the module valve.
I am confident that it must have had an installation error since it is low mileage and nothing at all anywhere seems to have been molested in any way. When I get back to the unit this week if times permits I intend on trying to lean the dash panel out without breaking any plastic and having a look see. Thanks again for your informed ideas. Big help!!