As you probably know, when you turn the key to the first detent, all lights on the dash should light, then they drop out when you fire it up. And that car is a rocket so if you are having problems then it is in limp mode. Why don't you go to the Benz forum, 140 Section and pose your problems. There are many 120 owners there (including me). I'll post this then find the exact address for you and re-post.
Anziani
'97 CL600