Hi Wolfgang,
I think the best way to simulate the real life is to disconnect the linkage and move the lever by Yourself. By moving it up and down You should hear the compressor go on and the pressure relief valve open alternately. One possible problem (that I have on my -95 RMW) is that the relief valve is stuck. I have bigger problems with my RM so I haven´t dug any deeper in the matter, but You can quite easily remove the compressor from it´s place behind the front bumper on the drivers side. You just remove the plastic cover from under the car and You see the compressor. I tried to get my relief valve unstuck but I´ve given up for the moment and just disconnected the system. Please post any success or discoverys You have, it will help me and others!
BTW, I´ve opened the lever and seen electronics inside so I´m not sure if You could short any wires directly to simulate the levers function, it may be a bit more elaborate than that.
Here´s some pics of the levelswitch:
Hope this helps, even if the thread is getting a bit old
