I appreciate the quick response, but I'm confused.
When you say both sides of the coil are you referring to the primary and secondary or do you really mean the + and - as stated in your post?
I believe I understand how the coil works. The primary windings are energized, when power is cut to the primary the more dense secondary windings become "induced" stepping up the voltage.
If you don't mind, would you explain the proper method for testing this coil with a light or DMM. (where to connect the leads for each test)
Unfortunately I don't have another car to test with, nor do I have a scope.
Is there a test point on the ICU so I can test that it is powered and has the inputs?
Since you mention that the ICU is a common failure on cars of this era can I rule out the crank sensor? (does this car have a crank sensor?)
1983' SL500 euro