Mercedes - Ignition Control or Overload Relay

I am helping a friend troubleshoot his 1991 Mercedes 420SEL. It will not start. We determined it is not firing (no spark from the coil).

We have been told it is either the ignition control unit or that something is triping the overload relay. How can we determine which one is the case?

Is the overload relay normaly energized and become de-energized when there is a problem? Or Vice Versa.

Any help would be greatly appreciated.

Thanks

Overload relay would be my first suspect... it is in your fusebox... a silver relay with a red fuse on the top. Make sure the fuse is good.

Overload relay, if not working will not let you start your car.

It was the Igniton Control Module. Replaced it and everything is fine.