Thanks for the link. I need to study the document. It seems some pins refer to multiple possible systems. How do I know which applies to my car?

I think the harness is good, because don't see any cracked insulation at the fuel injectors, or at any sensors. I only own the car for 6 years, but I assume the harness was replaced at one point.

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2004 E500 4Matic 138,000 miles