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Most wiring harnesses are no longer available nowadays. Good used harnesses are very difficult to find for many models. So the only option is to repair original wiring harness.

Engine harness rewire is a very labor intensive process. Some harnesses have more than 400’ of wires to replace. To eliminate possible errors and maintain original wire length it is recommended to replace just one wire at the time. That way each wire will be the exact same length for all connectors to reach their destinations. After all wires are replaced the whole harness needs to be wrapped preserving original exit points. Then main connectors need to be resealed. And at the end it is a good idea to pull schematic diagram and double check continuity from each pin on the main plug to each connector. Therefore the repair takes very long time. Some harnesses can take a day to rewire while the others can take a few days to repair.

Before considering rewiring of your existing harness check with a local dealer for a price of a new harness. In some cases the new harness is still available to purchase. But unfortunately nowadays most harnesses and no longer available.

If you want to buy new harness I would order it from dealer according to your car VIN number. The best option is to double check the part number with your original harness. Most of them are special order items and sold without possibility of return.

I had rewired many harnesses in my days. Some came from overseas from right hand drive cars. AMG and diesels harnesses were no longer available for years. So the only option to keep the car on the road is to have existing original harnesses rewired.

Above you can see some videos of rewired wiring harnesses.

Feel free to contact me for more information.

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All 1992 to 1995 S-class, 1993-1995 SL-class, 1993-1996 E-class, 1994-1996 C-class Mercedes Benzes have a major problem-biodegradable wiring harness insulation. Insulation flakes off injectors upper wiring harness, throttle body harness, starter/alternator harness, Mass Air Flow Sensors harness ( V12 engines). Wires short together and cause serious problems.

This problem is not only inconvenient but also dangerous. Shorting wires in V8s and inline 6s can make an engine stall. Shorts in mass air flow sensor wiring can totally destroy V12 engines. Injectors wiring shorts make engines misfire and even shut down in some cases.

I learned about MB wiring harness problems when I bought my first W140 1992 500SEL many years ago. I bought it cheap to restore as the body and the interior were in pristine condition. One of many problems with that car was deteriorated and shorting wiring harness. Sometimes engine would stall when I made sharp turns. One time I was making a sharp turn and the engine stalled in the middle of an intersection while another car was approaching. I tried restarting the engine putting the transmission in neutral and the engine restarted. That was a very close call, almost a t-bone accident. Right after I got back home, I parked the car, removed and rewired the injectors wiring harness.

Different Mercedes cars have different wiring harnesses. Some engines have just one large harness throughout the whole engine bay. Some models have few harnesses. V12 engine, for example, has upper harness, lower harness, mass air flow sensors harness. All have biodegradable insulation.