I just replaced the engine wiring harness on my 93 300E due to deterioration of the wiring insulation which caused engine problems. Cost a little over $900 for the harness, and I installed it myself. I've heard that the deterioration is because MB used biodegradable insulation. Isn't that the most brilliant engineering design you've ever heard of? (note: I'm being sarcastic). I'm curious to know if all the other wires in the car are like this.