1992 SL wont start-cranks but no idiot lights
 

Here's the scenario:
My 1992 500sl wouldn't start. The engine would crank but
wouldn't start. I noticed with the key turned to the final on position,
only the srs light was lit-no other idiots lights were on(which they should
befor the engine crank). The windows would not operate either.
after numerous attempts to start the car-i called mercedes roadside
assistance. Before they called me back, I checked fuses-no problem.
I finally turned the hey to full on-waited 20 secs, noticed that
the idiot lights finally came on cranked the engine-it started! I got
the car home but have been unable to start it. any ideas would be
appreciated. the car has 97K miles.

Problem Solved: SL cranks but wont start-also solved ASR problem
 

Follow up to my previous post. Problem was diagnosed and resolved by replacing the ignition switch. $97 part +3 hrs labor. This also solved my intermittent ASR dash inicator "light-on" problem.

My 96 sl won't start this week either, how did you get it diagnosed for the ignition switch?

Ignition switch because ignition circuit was not engaging; the coils were not receiving power, and the idiot lights were not coming on (starting is a separate part of the ignition circuit). On the pre-mass airflow systems ('92 and earlier), starting ether goes a long way in testing if the ignition circuit is energized (EZ does it, or you'll start the car on fire), but so does a voltmeter or scope. On a post-'92 with MAF sensor, if your blower motor doesn't engage and your fuel pump doesn't cycle, ignition switch is a likely culprit

You'll need to be much more specific on your starting problem if you want help diagnosing it (turns over but doesn't start, doesn't turn over, etc.).