What years and models have bad wire harnesses.
 

I have a 1996 SL600. Are the engine wire harnesses in this vehical OK how can I inspect.

John Roncallo

1996 engine wiring harnesses are supposed to be in the clear, but with all that heat in the tight engine comparment, who knows?

Generally speaking, all 1993-1995 models have bad enginen wiring harnesses.

1992 400E's and 500E's have bad harnesses, too, but 1992 300E's don't.

Go figure.

I think it covers the 1992-95 S-Class models.... maybe give or take a year.

I think the E-Class models were plagued as late as 1989-90?

Hmmm... What about prior models. E models go as far back as 1986 I recall. Is a new set of wiring harness expensive? What can you buy them besides the dealers.

The 1993 300E (3.2), 1993 300E 2.8, and 1994-1995 E320's are bad because these years have a different engine and fuel injection system / ignition system than earlier 300E's from 1986-1992. Thus, they have a different engine wiring harness.

The dealer is the only source of them AFAIK
There is a long thread running on this subject, here:http://www.peachparts.com/shopforum/showthread.php?t=128181

I was just looking at a car on eBay that the seller admits had a bad harness: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=160059464319

it cost the owner $600 labor and $1000 for the part to fix it:
http://www.lomilecollector.com/ab124.jpg

I saw three vehicles with bad engine harnesses in one week at the Indy where I worked, they were a '94, a '94 and a '95. E320 are very common with this problem but thanbksfuly neither of my '87 300D's have failed. Its more a problem in the later 124 years but there are 202's with the same issue

this is from a 140 chassis:

You have do a bit of careful digging to see if you have any problems.

http://v12uberalles.com/MAF_rewire.htm
http://v12uberalles.com/throttle_actuator_rewire.htm

Ew..... those look dreadful. :uhoh2: Looks like a fire just waiting to happen. :rolleyes:

Thanks for the info. It looks like I may haved dodged a bullet.

John Roncallo

I will have to check my service records but I could of swore i have reciepts from the previous owner who changed the throttle sensors or throttle something??? About 1,300 bucks?? I could be wrong and will have to double check, but would changing that be a good thing ( to me) since this seems to be a problem??

I would only change the harness if it is bad.

A mercedes technician would easily be able to tell if it's bad or not.

Is heat the main culprit that causes wire harness failure? I always assumed it was continuous bending and flexing that caused wire to break.

Tons of internet info on this. Has to do with environmental friendly insulation of wiring. Turned it disintegrated over time in engine compartment conditions.

Steve

Mercedes Benz used a wire insulation material that was unsuitable for the high-temperature environment of an engine compartment. Rumor has it that it was developed to be bio-degradable in an effort to be environmentally conscious. Unfortunately, the insulation degrades in the car. There are other wires throughout the car including inside the passenger compartment that suffer from this as well. But heat drastically speeds up degradation, hence the wires in the engine compartment failing more often. Flexing doesn't help either.