Re: What is the root of this BMW design flaw in all 3,5,7 series BMW trunk wiring looms?

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On Thu, 14 Mar 2013 01:03:56 +0000, Arthur wrote:


Might also want to add alt.autos.bmw
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dpb wrote on Wed, 13 Mar 2013 20:15:16 -0500:

All the vehicles are five to ten years old'ish.

The vehicles are all over the world. Same problem everywhere.

Yes. All the wires have been identified and all the circuits involved are implicated variously, e.g., KNOWN LOOM WIRE CONNECTIONS: 01. Red/yellow line = 2 @ x712 -> trunk lid light (positive) 02. Red/black line = 1 @ x1191 Rear lid lock switch (positive) 03. Gray/yellow line = 3 @ 1377 -> tunk lid locking switch (open signal) 04. Brown/gray line = 2 @ x709 -> left license plate light (positive) 05. Gray/Brown line = 4 @ x311 -> zv drive (lid closed) 06. Gray/black line = 2 @ x710 -> right license plate light (positive) 07. Gray/Green -> 4 @ x311 -> zv drive rear lid (positive) 08. White/ Brown line = 3 @ x311 -> ZV to luggage compartment light 09. Brown = 1 @ x709 -> left license plate light (ground) 10. Brown = 1 @ x710 -> right license plate light (ground) 11. Brown = 5 @ x311 -> zv drive ground 12. Brown = 1 @ x1377 -> trunk lid locking switch (open signal) 13. Brown/blue line = 2 @ x1191 Rear lid lock switch (unlock) NOTE: (majority color[s])/(line color)=(pin number)@(connector number -> description Sizes are 0.35mm2==!AWG, 0.5mm2== AWG, 0.75mm2==AWG

Mostly it's the license plate light, the central locking system, and the trunk lid which are affected.

Same thing BMW always says. Replace the entire trunk wiring loom every five years. BMW Part number: 61116907260
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"Arthur"

** Or use silicone coated wire and do it just once.
.... Phil
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Phil Allison wrote on Thu, 14 Mar 2013 16:24:59 +1100:

Here's a picture of the loom, laid out (on a BMW E46 3-series): http://www.bimmerfest.com/forums/attachment.php?attachmentid &5914&d97298236
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VinnyB wrote on Thu, 14 Mar 2013 05:24:43 -0500:

These 3,4,5 series BMWs are some of the best handling and safest vehicles on the planet. The M62, M62TU, M54, M52, & M52TU engines are bulletproof, and the suspensions superb.
Yet, part of owning a bimmer is fixing it yourself. Otherwise you'll go broke with the repairs. I know of scores who have "repaired" their trunk wiring loom - but I don't know of any who went to the stealer to have it replaced.
I was only answering the question of what BMW says to do. We all work on our own vehicles so we repair them ourselves.
Cost to "repair" is about $20 give or take - but the real question is why it breaks in the first place. It looks like, from the discussions, a combination of poor choice is insulation plus a badly designed snorkel.
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On Thu, 14 Mar 2013 06:18:22 -0700, snipped-for-privacy@optonline.net wrote:

Maybe. But why does it always fail at the same spot.
That can't be due to the poor choice of insulation, can it?
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Because if you make a loop and you open and close it over and over again, it will fail in the center of the loop where the angle of the movement is greatest.

No, as you'll notice the conductors are breaking too, not just the wire. So it's a poor choice of insulation AND stranding. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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On 03/14/2013 08:23 AM, Scott Dorsey wrote:

respectfully and completely disagree on that. the stranding is perfectly fine if the insulation remains intact. once the insulation cracks, then you have substantial strain concentrated in just one spot. even fine wire high count stranding will break if subject to such a failure.
the fix is both better wire insulation that doesn't become brittle, AND re-routing to avoid the elbow bend. then you can keep using cheap wire and don't need to spend money on the expensive hi-flex stuff.
--
fact check required

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i had the exact same thing happen in the rear door wiring in a 95 toyota camry.
Mark
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-

snip
my wife broke the inside passenger side..
i've learned to use only two fingers to pull on the handles, don't grab them.
i agree they are not very rugged... but it's about the only flaw i've found with that car (knock knock)
besides the rear door wires which i understand like the BMW is a very common spot for wires to break on this car...
and interestingly the rear door is used maybe 1/100 of the time compared to the drivers door so you would have to think there is something "special" about the way those particular wires are designed and/or built to make them break before the drivers door wires break
Mark
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On 3/15/2013 5:36 PM, Mark wrote:

The inside handles seem to be designed to break at the 8 to 10 year mark. The have a slot molded in to the highest stress point, I might add I don't see any reason for it. Other than to help the dealer sell replacement handles. Other than the door handles I'm a happy Toyota owner, had a Camry, have a T-100 still a sharp looking truck, have a Lexus and an Avalon. My wife is a persistent patient shopper, and will wait until she finds a great used car at a steal. Mikek
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Of course it can be. If BMW uses some hippie green insulation that isn't as pliable as other insulation, then the insulation will crack. We can't do a forensic investigation from some pics that don't show how it's mounted, how much it moves, what tensions are on it, etc. But I'd bet that area has more bending, tension, etc than the rest of it.
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On 03/14/2013 01:11 PM, snipped-for-privacy@optonline.net wrote:

Yes, that much is true. Someone had mentioned that having the wire in that area flex in torsion would be preferable and I agree with that statement as well. Would be simple to have accomplished by having the hole in the body offset by a few inches (actually as far as possible would be preferable) from the hole in the trunk lid, and using a correspondingly longer rubber boot. then most of the flexing of the wire as the trunk lid opens and closes would result in a slight twisting of the wire rather than a sharp bending.
The same holds true for wiring running from a body pillar into a door e.g. for power mirrors, windows, speakers, etc.
nate
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wrote as underneath snip

Have to be extra vigilant to water rundown in your scenario which for the wiring longevity agree would be much better! C+
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Nate Nagel wrote on Thu, 14 Mar 2013 06:30:59 -0400:

Luckily the door wiring on these E38, E39, and E46 (7, 5, 3 series) bimmers is just fine. It's just something wrong with the way the trunk wiring loom is designed that makes it crack in at the same point in all these vehicles.
Now, don't even get me started on the BMW window regulators (which constantly break on all these bimmers!).
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On Thu, 14 Mar 2013 20:14:01 -0400, Nate Nagel wrote:

The bimmer handles well, and the power train is phenomenal.
However, the window regulators break on almost every BMW older than about 5 years, while the blower motor final stage resistor (FSR), aka the final stage unit (FSU) will fry itself more than once on every single bimmer ever built in the late 90's and early 2000's.
The VANOS seals are made of a material that won't last the warranty period; and the Bosch 5.7 ABS control module was placed far too close to the engine for cost reasons, which fries almost every single one.
The DISA valve, which appears to be an amazing engineering feat, is practically designed to loosen the pin, which, if the engine ingests that steel pin, will wreak havoc on the valves as the pistons pummel it to pieces (there is nothing between the DISA valve and the intake manifold!).
The almost criminal design of the DISA is dwarfed by the clearly deficient design of the cooling system, where almost every bimmer older than a few years has had a catastrophic failure of, and very many multiple failures. Thousands of bimmers every year are destroyed by owners not realizing that a single overheating episode causes cracks in cylinder 3 (e.g., in the M54 engine) that essentially turn the otherwise fantastic power plant into so much rubbish.
And, there wasn't an E39 ever built (5-series, 1997 to 2003) which did NOT have the cluster and MID pixels turn to unreadable junk within a few years of manufacture (due to the infamous "pink tape").
Likewise, not a single E39 is immune to the horrid choice of PBT plastic for the headlight adjusters, turning $1000 fiber optic Halogen H7 and Xenon headlights into veritable candles within a few years of the heat baking the plastic.
Likely not one E39 hasn't had its power steering hose leak under the fluid reservoir, and not a single E46, E39, or E38 (3,5,6 series) bimmer hasn't had the CCV valve fail on them (i.e., a PCV valve which costs hundreds of dollars to replace, frequently).
For the V8, they all have valley pan gaskets leaking, and all the bimmers I'm talking about have had their thrust arm bushings tear.
Probably not a single bimmer of the categories above hasn't had the vapor barrier leaking (due to an extremely poor choice of design coupled with lousy sealant); and half the bimmers have cables slip out of the otherwise fancy seat, causing the infamous "seat twist".
I could go on (and on), (e.g., more than half will have the windshield washer pumps leak, and a huge percentage will lose their jack pads, while a healthy percentage will melt their center brake lamp housing, and even the roundels will chip away at the car wash until nothing but silver is left).
The funny thing is that BMW DOES know how to design a powerplant.
It appears that the Germans in Bavaria simply 'care' about some things (just count the ashtrays, for example, and then compare them to the unanimously ridiculous cupholders of the E39 era) while they don't care about others.
Clearly BMW cares about handling and efficiency of the power train; yet, just as clearly, overall product quality is NOT even on their radar screens.
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On Sat, 16 Mar 2013 05:28:52 +0000, Bimmer Owner wrote:

Ooops. 3, 5, and 7 series (embarrassing typo!)
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On 03/15/2013 10:28 PM, Bimmer Owner wrote:

ok, you're not going to like a lot of what i have to say, so i'm going to preface this by reminding you that i recognize that you may be sincere in what you believe - so don't take all this personally.

bmw's power trains are indeed "phenomenal", but for entirely different reasons than those by which others would measure.
bmw are pioneers in transmission life limitation. gm and frod used to do this by simply using cheapo clutch packs in their automatics, and cheapo steel in their sticks so they'd wear out or spall respectively. bmw didn't like these failure modes, so, not content with "sealed for life", they decided to design fatigue /into/ their cogs so they'd fatigue and break. [the beauty of fatigue is that you don't get "whiny transmission" or slippage symptoms that develop over time - one second it works, the next, it's a catastrophic failure.] i know this because one of my old profs was their outside consultant, and it was interesting to us as students because the metallurgical problem was how to ensure that individual ratios would fail when each one operates somewhere within the three [very different mechanism] fatigue "regimes". it's a "phenomenal" technical achievement and one that bmw paid a lot of money to solve. all the majors are now reputed to have followed their lead to some extent. the real kicker is that it costs bmw ~20% more in materials and q.c. to ensure this life limitation, but the mba's did their math and it pays because it causes big ticket repairs to vehicles that are depreciated thus ensuring that the vehicle gets junked.

it's not cost dude. see above.

for a company that spends hundreds of millions each and every year on research, [although that's substantially less than they spend on advertising!] do you really think all that is simply oversight?

not from where i sit they don't. single row timing chain, poor materials, both are manifestation of their overall design philosophy - they don't sell you a car, they're selling you a period of usage with a whole bunch of marking brainwash attached.

no they don't - they use macpherson strut. if they were serious, they'd use wishbone.
now, bmw are at least smart enough to have realized before most others, porsche included, that rear suspension is crucial to making a cheaply made car handle better, so they do at least concede to a little extra expenditure on that, but by definition, any front suspension that offers no camber control is just cheap junk.

it most definitely is. bmw are the pioneers of modern life limitation control. nobody has spent more on ensuring that whatever they use works for a closely defined period, and not a moment longer. as said before, it costs more to do this, but it pays. customers buying new are snowed into believing this "ultimate driving machine" advertising [the ultimate meaningless tagline!] so they don't care. and second [or later] owners have no recourse. it gets older bmw's [and their parts] off the road, and keeps sales up.
--
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Everybody does this, though. This is how cars are designed. I believe that GM was the original innovator of the concept, at least according to my old statics professor who had been a GM engineer in the fifties. He was very enthusiastic about the whole concept of designing for specific failures.
That said, I have 480,000 miles on the transmission in my old 2002, and I had a Chrysler Laser that went through five transmissions before I gave up on the thing.

I think some of the failures, like VANOS seals and the DISA failures, are the result of trying to push the technology too hard too fast.
And some of them, like the perpetually underdesigned cooling systems, are the result of German engineers not understanding that the weather around the world is not the same as it is in Bavaria.
But some of them are the result of typical German Engineering Disease, where engineers will never use one part to do a job when they can use five.
Still, when I drive the 2002, it makes me smile. I'm willing to put up with a remarkable amount of crap for that. Not everyone is, but that's why they make so many different kinds of cars.

That is the philosophy of the entire auto industry and singling out one manufacturer for it is disingenuous. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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On 03/16/2013 10:03 AM, Scott Dorsey wrote:

correct. i'm referring to the technique which bmw use - as i said, the "traditional" approach was having stuff wear out, which customers hate. sudden failure is the way to keep them all hooked, and particularly with bmw, "you must be a hard driver - it's the price you pay for driving a 'sports' car" excuses that go with it.

also correct - they tried to get into this stuff in the late 70's, didn't get very far, and didn't get it figured out [with outside help] until the early 80's. there are plenty of old bmw's on the road, but there's a honking great gap between them and anything older than ~10.

'nuff said!

it could just be incompetence, but seals are well known, the materials are well known, so there's no real reason for it to be oversight. especially if you read some of the german technical literature - they have multiple phd's crawling over every slightest detail.

germans travel the globe dude. they know /exactly/ what they're doing. and no cooling system fails on their target market owner - the one who wants a new "ultimate driving machine" every three years.

part of that is keeping it complicated thus helping to ensure that only /their/ shops work on their vehicles. why else would you have a 7mm allen socket on a brake caliper pin when 6 or 8mm would do and is widely available??? and bmw pioneered the "check engine light" concept and tried to lock it down so that only /their/ dealers could service their cars. fortunately, independent repair shops lobbied and congress stepped in on that one. [initially at least. we now have all the proprietary "tier two" codes which can be locked, but that's a war of who lobbies the most.]
the other part is that their design teams tend to work in isolation. each single component can be well designed, but having them all work together wasn't part of the original spec.

sure - it's the last of the era where they had the "good" part of the engineering figured out, and before the mba's took over.

i'm singling them out because their efforts at life limitation and lock-out are well over and above that of any other. "sealed for life" transmissions? ygbsm.
--
fact check required

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