Does anyone know the real deal on w140 wiring harness??

I have heard from several independent mechanics that these should be replaced on my 1995 s420 because of factory defects. My dealer refused to change my harness (which is still under warranty) because they assert that their visual inspection did not result in a reason to change it. One of my mechanic friends said that I should have it changed because a defective one could fry the controller modules.

My engine wire harness (95 S320) was replaced by MB. The engine wire harness insulation become hard, due to heat for the engine, and type of wires used by MB.

I suggest you to look over all the wiring under the hood, I am sure you will crack wiring.

jack

The wiring harness that mercedes used to put under the hood of their MBs during the early 90s suffer a lot from hardened insulation and connectors. These hardened parts crack as soon as you touch them and therefore some of these engine wire harnesses are changed under warranty...
I renewed some parts of the engine wire harness in my 1990 300SL-24 as well. A lot of broken connectors and cracked insulation parts...

greetingz,