Originally Posted by Bikerbill
That would require a connection to the PSM module that I think is an extra cost item from Mercedes. Mine just happens to have one along with a 2nd battery under the hood. Neither of which I believe are normally ordered by Airstream.
Direct from the MB brochure: The Parameterizable Special Module PSM control unit forms the interface between the vehicle and the electronic systems of the body manufacturer. The PSM control unit allows the body manufacturer's
electronic systems to read vehicle information and control vehicle functions (e.g. the central locking (ZV)) via the Controller Area Network bus class B (interior) (CAN-B).
My 2013 AI on 2012 Sprinter has the PSM (option code ED5). I think most AIs have this option. The idea of controlling the step by the gear selector is a great idea. However only the Sprinter Sales Engineering Team can provide the PSM software to enable functions. I did notice that gear selector position is an available parameter from the Engine CAN. But only Airstream with help from Sprinter Engineering could enable this feature.
If you are interested in technical information on PSM see attached file.