I've been reading the comments and opinions concerning the MB engine wiring harness issue on this Forum for a couple of years now with great interest. I've seen several posts warning of potential fire hazards. Over the years I've seen rear window heater relays fail and melt wires. I've seen blower motor wiring overheat and melt. I've seen power seat wiring chafed and burned up. I've seen seat heater elements overheat and toast seat covers. I've seen water soaked fuse boxes get hot enough to melt the plastic covers. A few years ago I replaced the entire frame floor/body harness on an 02' S500, along with the rear fuse box and SAM because of melted wires. (MB bought the car back because we couldn't get the smell of burnt plastic/smoke out of the car) I've seen countless wires burn up due to pinching, chafing, crushing, etc., and sometimes cause minor damage from the heat produced. One thing I've NEVER seen is a fire caused by a defective engine wiring harness. Never. Not one. Not even a hint of something getting hot enough to burn.


As far as it being a safety issue? The OVERWHELMING majority of affected vehicles exhibit relatively minor problems at first. An intermittent crank/no-start is probably the most serious problem when the harness begins to deteriorate. Check engine lights are much more common and usually amount to little more than a nuisance. I've never seen any MB simply die without warning while driving down the highway(which IS a serious safety issue)due to a defective harness. To put it simply, the symptoms are minor at first, and increase in severity as the harness deteriorates further. If, for whatever reason, the owner ignores the warning signs, they shouldn't be surprised when the problem gets worse. Please remember, this is only my opinion, but it's based on what I've seen in the seventeen years I've spent working on these cars.


Lastly, don't be surprised at MB side-stepping the issue. I could be wrong, but it's my guess that the people complaining the loudest aren't even the original owners of the cars in question. In the eyes of MB, there's no comparison between the original buyer and a second-hand buyer(unless it's a STARMARK/CPO). You may reply, "what difference does that make?" or "true, but why would I ever buy a new MB if they won't stand behind the old ones?". They'll tell you they offer one of the best factory warranties in the industry and they'd be right. MB is probably guessing that most of the people complaining will never be in the market for a new MB anyway. Besides, MB has had way too many quality issues in recent years to worry about cars that have been out of warranty for at least five years.

We live in Pickering Ontario & our local MB dealer cannot diagnose cars older than 1994. I guess I have to go to Radio Shack & buy a lead. Don't you think they could rent one?

Tom-R

I understand your theory regarding MB's stance on the wiring harness issues and the incidences reported via second-hand owners, but I have to ask:

Why was the same stance taken for the harmonic balancer and the ring coking ML engines from the improper FSS intevals with dino oil? Those issues turned up with "under warranty" vehicles and first owners had to fight uphill battles (many lost) with MB to get them to admit there was a factory defect that required an admission and a service campaign to fix!

Ironically, I have had to deal with the harness and the balancer with out of pocket $$$ (both vehicles out of warranty and/or past goodwill mileage). Fortunately, the ML left the showroom with synth oil and stayed on the program consistently.

I love my MBs, but Honda and Lexus does a better job in this arena...and they don't discriminate against new car vs. second-hand owners, etc...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

Good question G-Benz. The answer is simple. The legal climate in the U.S. dictates the strategy that companies must follow to avoid being overrun with lawsuits. The strategy is always the same. Deny, deny, deny!!! It's sad but true, and it's not only MB who does this. As a shop foreman, I have access to information such as pending technical bulletins, campaigns, etc., well in advance of their official release. The reason? MB dealers need information as it develops. We can't wait weeks or months for the MB legal department to approve the language used in the publication of information that will be made available to the general public. The information is passed along by word of mouth, completely un-filtered. It's an absolute necessity and it serves in the best interest of our clients'. I do think MB should have done the right thing, but I think they're past the point of no return.

I dont know how many first time mercedes owners can AFFORD a new mercedes. My First mercedes just a couple years ago was a 1973 220d. A car I was very happy with (minus all the smoke) and I went from there up to a 1994. I am ready to upgrade now (although I will probably go with a bmw or lexus) but most first time owners- young families, etc) simply can't afford to buy high dollar car. Making this into a money/income issue should never mean Mercedes should not fix their problems.

Also, part of buying a new MB is the idea that it can be sold as a used car later and will retain value -- so, without persons buying used MB's there would probably be very few who would want to buy new MB's or certified used MB's.

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Dan

1986 560SL (52.5k miles) sold 11/24/04

1987 560sl (55.6k miles)

Volvo had lots of engine wiring harness problems, too.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

Volvo = Ford !
Any other questions?

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2007 C 230 Sport.

Volvo had problems before Ford

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

Yes. But it can only get worse.
Ford has had MAJOR wiringproblems for many years,
Can you say VEHICLE FIRES.
Small wonder, with the mess of spaghetti wiring they have under the hood.

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2007 C 230 Sport.

my saab caught fire the other day... and the
wiring harness played a great roll... the batter is located
near the turbo... so when the turbo failed oil went every where..
the oil on the wiring caught fire and i had an engine fire that required the
fire dept....

so wiring harness probably wont start a fire in the engine compartment until
something like this occurs... but it is a real possiblity... just think about it..

we have electrical wires actually attached to the injectors... so ad 10 years
and a car fire is an easy thing...

But, on Ford's the wiringharness STARTS the fire.

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2007 C 230 Sport.

Apples and Oranges. Frankly if I got an engine fire or engine/tranny failure in a Ford or GM I would say "Hmm well ok" and move on. On a BENZ I would be very very upset especially considering I just spent nearly double the price for the car.

On the question of second hand owner treatment, there is no doubt that MB treats second hand owners worse compared to the competition. I think Mercedes does it because of cost. I would think it would be too expensive to keep a CIS expert on staff. But some of those second hand owners could become life long Benz supporters or buyers if they were just treated with a little respect right? There is also the problem of benz owners with older benzes equating their current treatment at the dealer with the treatment they will get if they buy a newer MB.
My sister and I bought a second hand Mazda Protege from a Lexus dealer and we were treated like royalty, it was surreal! I was so impressed it took a lot of self control to not price a Lexus while I was there

So, can you show me a cheap Volvo?
That's what we were talking about.
See " Volvo = Ford ".

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2007 C 230 Sport.

iluvmils, wiring harnes problem is absolutely not like a slowly deteriorating mechanical problem. this isn't something that starts squeaking and as it gets louder demands attention.
check out the history of P.O. on my 95 e320:
130,355 - owner complains of steering noise, shop checked abs system for trouble codes, none found
139,685 - car runshot in traffic, hard starting at times. shop cleaned throttle, replaces splash pan. replaced aux fan
145,234 - car does not restart, check engine light on, high idle. shop ran diagnostic, found trouble code 003-IAT (sensor short to ground). replaced air intake temp sensor and engine coolant temp sensor. install new Overload Relay.
151,309 - check engine light, found codes 5,8, 10. replace mass air flow sensor, replaced coolant temp sensor, cleaned out egr tube.
151,896 - check engine light, found code 10. shop cleaned electrical connections.

Then I bought the car. the check engine light was on and had high idle. I replaced the TBA and car works fine...but for how long.
I think all the above parts failed due to bad harness. the P.O. got so fed up with the constant breaking down - every month another engine part.
I have not yet swapped the harness, and I'm wondering how long I've got before it eats another part.

I live in central jersey. If you'd like to have a glance at the harness I'd be thrilled to get your opinion.

currently at 160,080 miles.