I have a good one for all the Mercedes Techs out there!!

My Idle speed control module burned out the other day (yep, I could actually smell that awful smell on the circuit board) so I got a new one... but before I put it in I was told that the resistance of the idle speed control valve has to be 5 ohms or more or it will burn out the control unit again. I have never heard of this... is this really true?
84 500 sel Euro

Thanks for your help!