Mercedes-Benz

Anyone experienced in the electronic ignition on The Merc 500 SEC.

It just cut out and stopped and I'm making the assumption its in the
little box.

I have no spark and when the "black" box was opened it smelt like
something has been getting hot. They have a Bosch electronic box.

What I would like to know is how repairable are these things and can you
buy parts or would anyone have a circuit diagram.

Thanks

I doubt you will find schematics for the control boxes since Bosch
likes to protect their intellectual property.

If you have verified the position sensor is ok (should be the thick
green wire) and all of the wiring to the coil, most likely the FET's
(field effect transistors) that switch the coil have gone. I would
start there if I was going to dig inside one of these. Be aware that
there is probably a conformal coating on the componenets so you will
need to se / clean this off before attempting any soldering. If
the repair is successful I would recommend spraying on some fresh
conformal coating over your repair.

Personally I would look around on eBay or a yard and see if you can
pick one up cheap to try first.