There's never been any evidence that the wiring for the rest of the car was supplied by the Swedish subscontractor that supplied the biodegradeable engine compartment harnesses, nor any evidence whatsoever that the other harnesses were made of the biodegradeable material.

Euro models seem to do, but the V8 W124s were never available in the UK market place, except for the special order 500E / E500 and that was still LHD. The 300E was the top of the range W124 in the UK until it was replaced by the E320. It cost about a 1/3 of the price of a good house. If you wanted, leather (1500), radio (200 ish), electric seats, a/c (2500), alloys (1500), illuminated vanity mirrors (650), etc, it soon added up.
On the upside, there was the Hughes of Beaconsfield twin turbo conversion if your tastes and wallet extended that far.
Our old clunker estate was bought new by a London City based company director and even he could only manage the radio, towbar and puddle lights (it was supplied with only the two speakers in the dashboard, oddly enough).
It is close to worn out and quite battered, but is still the best MB that we've had: it is less rusty at 22 years old than our 1992 300 was at nine years old.

Swedish automotive stuff is usually rugged to the nth degree (said while thinking fondly - ish - of our 1980s SAAB 900 2.0, 8V, turbo), but didn't Germany acquire a Green Party Government at about that time?
Incidentally, that 900 turbo made the 300E feel sluggish by comparison, despite the engine being an obsolete Triumph unit.

Volvo also had biodegradeable wiring harness problems, as did several other manufacturers. Many over the years have tried to blame this on government but it's not plausible that the German government required some manufacturers to do and not others. This was an engineering screwup - by the manufacturers and the harness subcontractors who sold them a bill of goods.

No mindless speculation.

Mercedes won't admit that there is a problem so rule them out at a source of info.

1. Wiring on the engine will fail more rapidly due to high heat and flexing / vibration.

2. Under hood wiring is subject to a bit less heat and much less flexing / vibration.

3. Dash wiring is only subject to closed car heat and minimal flexing / vibration.

Has anyone looked for a maker mark on the harness tags to determine if the engine harness is from the same maker as body wiring? Supposedly Delphi ( Parts arm of GM ) makes the updated replacement harnesses.

Just for completeness.

SAAB and Triumph shared the initial design of the slant 4. They went their separate ways early on and I'm pretty sure almost nothing interchanges. I've had both motors ( 80 SAAB 900 and 19?? Triumph TR-7 ) side by side and they look similar but not the same.

In SAAB land, the original " B " motor has a in block water pump, 81 brought the " 2 B " motor with a conventional water pump, better head and eventually a 16 valve version.

As for your comment " . . . thinking fondly - ish - of our 1980s SAAB 900 . . . " I'm guessing you experienced " The SAAB fix of the day, if you don't do anything else all day, at least fix one thing on your SAAB "

1980 SAAB 900 , since 1985

There's also never been any evidence that the wiring in the rest of the car is NOT biodegradable. As stated a couple of times earlier in this thread, the under-hood wiring just gets the most abuse in terms of heat cycling, flexing and being disturbed for maintenance.

The wiring harness that goes to the tailgate of my 1995 E320 wagon (particularly to the rear window wiper and washer) has been flexed to the point where it doesn't work. It's one of the next jobs I'm going to delve into, but I would be willing to bet $100 that that harness is also "biodegradable" wiring (will take photos) and met its demise by flexing. I did not have this problem on my 1992 300TE.

It is VERY logical that the biodegradable wiring would be all throughout the car, not just in the upper and lower engine wiring harnesses, as well as INSIDE the ETA (on the 500E).

Cheers,
Gerry

Just curious, how do y'all know if it's the original harness, unless you were the original owner...? Many times the engine harnesses were replaced during the first few years (sometimes under warranty, as on my '94). Only way to know for sure is to check the date codes on the harness using the links Gerry posted above. Ditto for the ETA.

:boat:

Like gerryvz, I've had more than one problem with the wiring where it flexes at the trunk. That wiring is rather stiff. Plus I've got two more cars that are older and with more miles than my 95 E320. The wiring on these other cars is more pliable.

Is this proof that all wiring in my car is biodegradable?... no, but it's an observation worth noting.

No, that's flawed logic from the get-go. Engines and chassis are made in different factories with different engineers, different purchasing departments. Here in Arizona a car sitting in the sun in the summer can get to 160-170 degrees inside, for months every year, but there's never been any sign of widespread systemic failure of the chassis harnesses. But my point was not that I know, but that the poster stating it's all biodegradeable and doomed to fail was speculating. The trend just isn't there almost 20 years in.

There's a pretty bloody big difference between 160-170 degree temperatures and far higher underhood temperatures that cause the insulation to bake off the wires inside the harness bundles and inside the ETA.

Also, because MB spec'd an increasing use of "enviro-friendly" materials and "full" recyclability of raw materials (as we know they did in the early-mid 1990s, and which is reflected in many design choices in the cars, particularly post-W124) when the car's life ended, it seems that such corporate mandates would apply to the entire vehicle, not just the wiring bundles. So while individual departments and design/manufacturing teams certainly made choices in materials and costs, they also were all operating under the same corporate mandate to optimize their decisions for recyclability and environmental responsibility.

My point was simply that there's no definitive way to tell, and no way NOT to tell, without doing a thorough physical/chemical analysis of various wiring bundles throughout the car to compare. However, it seems odd (and illogical) to me that MB would ONLY specify "bad" wiring for the upper and lower engine-bay harnesses, and inside the ETA, while every other length of wire on the entire car is of the traditional type.

I guess there's no real way to know; it is what it is and harnesses need replacement when they need replacement. We feed the beast and move on.

Cheers,
Gerry

Disagree
 

http://www.peachparts.com/shopforum/general-information/128181-mb-wiring-harness-failure.html

In Michigan; I have seen hundreds of these with the identical dashboard harness failure, many caught fire.


.

Outside my main wire harness. My oil level sender wire harness crumbled from changing out the sensor. When I replaced both the wagon hatch struts two weeks ago, there were clusters of wiring under the liner which I saw some deterioration of two of the wires leading up to the wire clusters (think it was near the right strut). But all the wires were pretty stiff..so I was extra careful while getting those hatch struts in. When I dove behind the instrument cluster to replace the speedo cable some wire bundles were pretty pliable while others felt fragile. But when I replaced the factory stereo head unit, there was a wire (to climate control module) the I had to repair as the insulation was definitely toast for a good 3-4 inches. So....that's my evidence that most if not all the wiring in wagon has the same bio-degradable insulation. My old 1993 300zx TT does not show any signs of the wiring insulation failure.

1995 E420 152k

93 300E 3.2 @ 220K
 

My 93 300E has 3.2 with 220,000 miles. I bought the car used about 10 years ago with 90K miles. Don't know if the wiring harness is bad but I am noticing things like the car will trigger alarm if I unlock and open from driver's door (my workaround is to unlock from the trunk). But this only happens in rainy season.

Also, the ETA has gone bad. Just took it off and saw wires (especially on the 7 smaller gauge wires) all bare. I'm working on manually fixing this with shrink tubing. But I'm afraid shrink tubing may not hold well because it has upper limit of 135 degrees. It can get hotter inside engine.