[Richard and Rhonda]

Then it makes perfect sense. When you dump the tag bags, the RHV will automatically put air into the drive bags to keep the ride hide at the set point. When you inflate the tag bag the RHV dumps air from the drive bags to keep the ride height about the same.
There has to be some sort of valving that kicks in when the tag axle switch is activated that isolates the tag from drive. Your data shows they are normally connected when the switch is in the middle.