Pre-empted by the desire to determine whether my car's CIS-E had the Fault Detection feature and whether it would tell me what ails it, I determined It Does, but It Didn't. See 1986 560SL Duty Cycle Madness for details on that experience.

In the afternoon, I returned to diagnosing my Idle Speed Control Unit (ISCU) per service manual 07.3-112 Testing electronic idle speed control. Previous test results were posted in Part 1 at 560SL Idle Speed Control Unit Test Part 1.