Originally Posted by hossmach

When you turn ignition on and the dash lights come on but no cranking from the starter, possibly the radiator fan blowing at full speed. That means the RCM (Relay control module) solder joints need resoldering. You can do two things, purchase a new RCM Part # A 170 545 03 05 that is a Mercedes Benz part or remove, disassemble the module, unsolder the connections and resolder. The dealer is must likely not willing or able to do this work, they rather sell you a new one. I rebuild this units and have two available.