If you want to replace the RCM with a new one here you go.

RELAY. APPARATUS CASE AND CONTROL UNITS for Mercedes SLK 32 AMG KOMPRESSOR (2001 - 2004). #1705450305

I remember going through this, in the end I just replaced mine and been fine. This will fix it for certain, that much I can attest too. German cars are more finicky about there electronics then say your domestics. My ram srt-10 will run fine with no name sensors from autozone, my srt-6 with throw a fit if its not OEM/Bosch.