calpatriot

Question on vacuum hose routing... car is an S4 N/A, stock. There are two vacuum lines that come around the back side of the engine (where they join hard lines) and come to two vertical nipples at the boundary between the UIM and LIM. They presumably are for the relief valve, and the switching solenoid valve... but which nipple is which; the front one seems like it should be for the relief valve, but applying vacuum there has no effect... valve may be defective but I want to verify the proper routing. Which nipple is for the relief valve?