Thought I would chime in with my M104 wiring harness experience last summer. When I purchased the car ('95 E320 wagon) in July 2004, the usual places for detecting a defective harness all appeared sound (as in, the insulation was not brittle and quite intact). The car worked well and I thought I dodged the proverbial bullet; it worked well until last summer and we were a few hours in the state of Maine heading for Canada. The car started to miss as we encountered grades or needed to accelerate. Upon arrival at my destination in Nova Scotia, I accessed this very website and searched on the dreaded harness. I discovered that to thoroughly assess the condition of the harness, the cover between camshafts had to be removed. I felt the wires beneath the conduit and it was quite "crunchy". I carefully cut into a section of the conduit with an Exacto knife and discovered the insulation on the wires leading to a coil unit was either missing or quite fragmented. Not having the luxury of time to accurately determine the source of the "miss", I deemed a wiring harness replacement was necessary before further diagnosis could occur. The purchase price of a new, replacement harness from the dealer was on the north side of $1,000 (U.S.). The harness was replaced and the "miss" never occurred again. I failed to take not of the manufacture date on the replacement harness. One can only hope that MB did not continue to re-introduce the problem by supplying the defective harnesses to their parts inventory.

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