Im going to throw my story in with dealing with this horrible code.
After throwing away about $400 (soldering irons, used RCM's, etc) on stuff that didnt work the right and proper way to fix this is to buy a new one. (this is after making sure your air pump works)
What finally fix this problem for me was a brand new RCM. They only cost 199+ shipping, and this was from a benz dealership in south atlanta. This is the link to a new RCM.
RELAY. APPARATUS CASE AND CONTROL UNITS. Mercedes SLK 32 AMG KOMPRESSOR (2001 - 2004) # 1705450305
Ive come to the realization that since this car is technically a German car, you cant jimmy rig or band-aid fix it like you would with say a camaro or a mustang, those are simple to fix. This thing requires new stuff to work right, not band-aid stuff that will allow it to work then fail again a week or 2 later. Thats my 2 cents.
Save yourself the headache and just buy a new RCM. They dont cost much and your car will run that much better since you have 5 new relays.