Your coach year model has a unique pneumatic control configuration that the symptom you described will happen if you have a leaky auxiliary air system. Mine is a 1995(with a year or two newer, the pneumatic logic was changed to avoid this issue), so I also have the pneumatic logic that will unload the tag axle air bags if the aux air pressure drops below a minimum pressure. The pressure at which this happens will vary due the mechanical components that initiates the dump. Simply stated, if your aux air drops below what the Norgren plunger needs to release, air will escape from the tag axle air bags during this transition due to low control air pressure suppling your tag axle raise/lower Norgren.

This is very complicated pneumatic logic and is difficult to explain in a message. However, if you would like to chat about this issue, I will be happy to share what I have learned. I have sent you my cell phone number in your private message box.

Hector