Mercedes EIS (Electronic Ignition Switch) Modules The Mercedes EIS (Electronic Ignition Switch) system is great in theory, the hardware being the switch is like a small socket in the dash to insert your key into - only, it is not a traditional looking key. It is more like a plastic lego-brick with what looks like an infra-red panel at the face of it which is inserted into the EIS socket on the dash. The key has a sequential code to…