For a period of time, Mercedes-Benz included wiring harnesses with biodegradable insulation around the wire. The upper harness is the critical one to replace and by now if a car from this period is running, it’s likely already been replaced. But the lower harness is often overlooked. My car was running well but look at the terrible shape of the lower harness! My mechanic was able to do a full rebuild of the lower harness and I took the old one home so I could show you.
