The unit commonly referred to as the "ZEE Unit" is only present in 599cc engine city-coupe and cabrios. 698cc fortwos have this function integrated into the SAM unit.

This is where your keys are coded to, but should not be confused with the receiver, located under the centre tunnel in the car.

To remove the ZEE unit, you must first unplug all of the relays out of the fuse box.

Unplug the main plug into the unit and slide out the side of the fuse box.

The front of the ZEE Unit.

The back of the ZEE unit:

To open up the ZEE, there are clips around the edge as shown:

This will reveal the back of the PCB:

It is almost impossible to access the front of the PCB without breaking it. Fortunately, this one was broken before we started: