Thanks for your response. I'll take a deep dive into the system this weekend and try to inspect each part to determine where the issue is.

I find it hard to believe that MB failed to document details on this system. Did they not use it on other models such as the W124 or W140?

I'll also try to hit some international forums to see if there is any information that can be hard from members with Euro cars as mine is an 88, which means that this system was around for a few more years abroad.

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With best regards

Al