I'm working on this vehicle and have no spark.. I have 12 volts to the coil but no high voltage going to the sparkplugs. Is the coil bad? Or the ignition module? And I'm not quite sure how to check the ignition module to figure out which of these 2 parts is bad. I have a power probe 2 and was hoping someone could give me some insight as to how to check both to figure out which one is bad. A diagram or detailed explanation is all i need. I'm a mechanic. Just haven't worked on a lot of Mercedes And don't have the means of looking it up on a shop computer.. Doing this work at customers house. Can anyone help?