Air Suspension Issues

[al perna]

Seems I have been having some issues with my air system . Our coach has the steerable Tag ,or following, which ever you prefer

well the way I understand it there should be a adjustable valve up on the cross member behind the Tag . Well all I have there is 2 3 position valves .

1 handles the supply and feeds the cylinder for the tag , then it branches off to a valve that feeds the tag and also has the 2 wires from the clippard valve to dump .

My question , does anyone have a clew where else the PPV could be ,and also why only 1 Tag bag would fill .

There are no holes or air leaks in the bags . Thank you in advance