Took the panel off to get at the pump for the winterization, there are lots of screw on connectors in there but nothing will fit the filter. Went back to the dealer and looked at another W210, same deal, filter is sitting in a drawer with no extra connectors with it. He is at a loss to explain how to hook it up or where it goes. Another dealer in the area has the filter that goes on the outside hose, will get one for next year.
Thanks for all who responded