Hi, I am new to this board. Signed up as I'm helping a friend sort out a few cars left to him by a family member inheritance. A 94 500E and a W140 S500. Is there a quick, easy, a definitive way (by looking or posting a photo here for you guys to look) to tell if the upper and-or lower wiring harness has been replaced. He can't find the paperwork from the dealership given the age of the car and it was never his to own, so I'm trying to help him look. If anyone has a foolproof and noob-proof way to tell, would really appreciate it.
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Easy and Definitive way to tell if Wiring (upper & lower) harness has been replaced?
- Thread starter mikelaca
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Welcome! Yes. Do a search on this forum - the label on the harness has two dates - ZD and FD. One of those dates is the production date. There is a big thread here on this forum that talks about this..
Sooooooooo many times —— a car might be running “fine” and the owner replaces the wiring harness as a precaution and cuts open the original harness for a quick look and says “ZOMG HOW DID MY CAR EVEN RUN?”
. It is a good idea to replace the upper/lower harnesses if they are original.
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Anyone in Europe who knows of someone reputable who can (re)build a NLA lower harness? Preferably in the Netherlands, Germany, Belgium or nearby?
I and probably many here would disagree on that. The car may run flawlessly with a bad harness, until it suddenly doesn’t, and the consequences may be expensive.
The horror of a harness on my previous E420 is a prime example. Ran perfectly, no issues at all. This is what the insulation looked like inside the old one:
I would not trust a Mercedes workshop with that advice. It’s a well known, well documented fact with the harnesses.
Derkabeldoc.de , good prices too. Doing my upper there. Edit: you send your old one in
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Kurth Klassiks sells a repair harness for the 034 and 036 lower harness. You re-use your existing large positive cable and metal brackets, and replace the rest with their supplied wiring.
Mercedes positive cable harness A1245403130
get a new harness with highest temperature resistance
There is a longstanding "sticky" note that tells one how to check their harness:
HOW-TO: Determining the age of your engine wiring harness | "HOW-TO" Tutorial Articles
See attached photos. The manufacturing date of the harness will be on the tag. If the date is 1996 or newer, the harness is not original. The new replacement harnesses made from at least 1998-up (possibly earlier) have improved insulation and do not fail after a few years like the originals did...
www.500eboard.co
Harnesses with an early 1990s manufacture date must be replaced.
Confirmation of Upper & Lower harness replacement should be amongst the first items stated/requested by a 500E/E500 seller/buyer. The answer is critically pivotal to a happy ending. Deteriorated wire insulation can be the root cause of so many performance anomalies.
The upper harness was replaced prior to my 500E purchase. I replaced the lower harness. Upon dissection, I was appalled at the insulation deterioration & was surprised I had not yet encountered any issues caused by it.
The "Go Green" good intentions of the wiring insulation did not prove well in real world application.
Confirmation of Upper & Lower harness replacement should be amongst the first items stated/requested by a 500E/E500 seller/buyer. The answer is critically pivotal to a happy ending. Deteriorated wire insulation can be the root cause of so many performance anomalies.
The upper harness was replaced prior to my 500E purchase. I replaced the lower harness. Upon dissection, I was appalled at the insulation deterioration & was surprised I had not yet encountered any issues caused by it.
The "Go Green" good intentions of the wiring insulation did not prove well in real world application.
