I am aware that in "The Pro's Tech Tips" there is the topic "Check you wiring harness" talking about this subject. Weeks ago, "blakebab" posted a message says that the HFM control unit is destroyed possibly by bad wire harnesses. So I re-check the harnesses on my '94 C280. There are two harnesses on the thermostat housing, one is "011 545 7128" and the other one is "011 545 8528". Both have star mark on them. There is another harness also a "011 545 7128" in front of the windshield washer reservior. The place it connects to has an arrow sign and "MOT" on it. All three harnesses show NO sign of crack. However, outside the wire, there is a cover or wrapper which is loose and not connected to the harness. Are these harnesses bad? Based on the part number, can you tell whether it is an original harness or a revised one? Also, are there any other wire harnesses I should be worry about? "blakebab" mentioned the dealer replaced the transmission harness. Where is it?

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Harry (94 C280)

The part numbers you've quoted are for the plastic connectors at the end of the wires. The problem is the "insulation" on the wires inside the harness that goes all over the engine(esp power for injectors & coils). Either open a small section of the sheath that the wires are inside of, or take it to a Benz only repair shop OR dealer that knows what to look for.