Thanks for the offer but no thanks.

I read that code readers are easy to build for this model but I don’t have the time or desire to screw around that way so a search for Mercedes 124 diagnostic code reader lead me to the following

http://www.ebay.com/itm/Mercedes-Diagnostic-Code-Reader-W124-300e-and-others-/330609004338?pt=Motors_Automotive_Tools&hash=item4cf9d50f32&vxp=mtr