I love numbers and data as much as any other German car enthusiast. I prefer to hear them coming from one's mouth as opposed to other orfices. It is for this reason i intorduce to you a textual state diagram in the form of a few simple questions and statements.

Statement #1: The the normal draw as specified by Mercedes is not enough to light a test light.

Statement #2: The normal draw as specified by Mercedes is nowhere near enough to drain a battery overnight.

Problem: Battery draining overnight.

Logic step #1: Because of statement #2 we know that there must be more then the normal draw on the battery.

Test #1: Grab test lightplace between one of the battery leads and the car. If it does not light go to Logic step #3, otherwise proceed onto logic step #2.

Logic step #2: Your light has lit, this means that based on Statement #1 there must be a draw more then the normal draw as specified by Mercedes that is also enough to light the test light. Continue to action step #1!

Logic step #3: We know from statement #2 that there must be a draw but it is not enough ato light the test light. Get your amp meter, and go to Action step #1.

Action step #1: Remove fuses till the light goes out or the amp meter drops.


If you have gotten thsi far you now understand that a test light, while not a replacement for a good amp meter is an extremely convenient way to diagnose electrical draw!