i read almost all the other posts that i could get my hands on. my '99 slk 230 stranded me yet again today! I think my situation is a bit different than the others. It happens intermittently...and only when i am out and about. It will be running just fine. I get in, turn the key and the dash lights/clock/odometer go out. and then NOTHING happens. it's just gone. everything. the power locks don't work. you get the picture. I have discovered that if i slam the door sometimes i can get it restarted. The dealership has it again (thought it was a bad radio last time) and i'm not sure they have a clue what to do with it. I probably will have trouble understanding the responses, but i will be happy to tell the mechanic the things i want looked at. Any input would be a huge help.

 

It sounds like a bad (loose) power or ground connection. Check battery posts for oxydation, all negative connections to chassis and positive (thick) wires in your electric distribution box under fuses and relays. Make sure all fuses and relays are inserted all the way in their sockets. Slamming your doors will make the bad connection to move and let enough electric current to pass through for normal operation. (my best guess)

 

I see you have a 99. Have your indy look a the K40 relay.