E320's have a pump near the fuse box and the relay module in the fuse box but i would know what to do heres a pic of the wiring, it does look like removing or disabling the relay would kill the majority of the ETS/ETC and you could kill the diagnostic wires at the same time to keep the ECU from knowing
Black wire is the relay it says so kill that and the diagnostic wires with a switch and your good?
Red Arrow to M1 =Pump
Blue Arrow to K4=Relay Module
