[Richard and Rhonda]

This has me thinking on how to tell if up or down solenoids are leaking. If down solenoids, then you could put soapy water on the open holes on back of the manifold. If the up solenoids, you could bleed the coach air pressure down, unscrew the air supply line to manifold and plug the manifold. If the ups are leaking then this would keep the air in manifold.