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

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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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wrote:

As long as it doesn't fail during the warranty period they don't care.
Is this poor grade wire mandated by regulations?

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I have seen a lot of cars over the years, and I have never, ever seen one that used anything approaching quality wire.
And that begins with the '72 Datsun I had, where all of the insulation turned to goo and every foot of wire in the body had to be pulled out and replaced.
Just take a look at what goes into airplanes vs. what goes into cars and you'll be staggered. --scott
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The price per foot will probalby do the same.
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On 03/18/2013 07:38 AM, Scott Dorsey wrote:

you're spoiled if you work on aero-spec stuff.
car quality goes in cycles - for some manufacturers anyway. in the late 80's, hondas used a higher grade under the hood - fine wire high count high temp high flex [though not silicone], and it's remarkably reliable. in the mid 90's they changed to lower flex, smaller cross-section, lower count, much more akin to the wire used in the rest of the vehicle - it still just about hangs in there, though i doubt it's million mile material. i'm pretty sure copper prices had a big influence on this.

planes cost a /lot/ more!
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Did they tin it? The lack of tinning is one of the things that annoys me about many of the cars of that era.
Silicone is actually a problem for cars because if you nick the insulation the cut will propagate until it becomes a break.

It wasn't failing enough, so they had to downgrade it. --scott
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On 03/18/2013 10:38 AM, Scott Dorsey wrote:

no, it's not tinned.
there are two schools of thought on that. on the one hand, surface oxidation resistance is a good thing. on the other, there may be a problem with tin in fatigue environments. i don't know this for sure, so if you know someone at work who does, it would be good to check - but tin has a weird deformation mechanism called "twinning" which changes the surface of the metal where it's occurred. given that almost all fatigue initiates at a surface, that /might/ be a fatigue initiator. how much it might be worse than oxidation, i can't say, but i know a lot of mil spec wire is silver plated, not tin, so i think it might not be simple cheapness preventing its use.

indeed, but that's not unique to silicone - many elastomers have the same problem.

maybe. it was was bullet proof - never failed unless abused.
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On 03/18/2013 10:38 AM, Scott Dorsey wrote:

Surprisingly, I apparently got one of the first '55 Studebakers that used the plastic-insulated wire rather than the cloth-covered wire that was used previously. It was still intact and flexible when I pulled the harness for repairs 5-6 years ago which made me happy as I was not looking forward to laying out for a new one.
nate
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jim beam wrote:

Makes me wonder about the door wiring.
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On Wed, 13 Mar 2013 23:45:12 -0500, Paul in Houston TX
is the root of this BMW design flaw in all 3,5,7 series BMW trunk wiring looms?:

Makes me wonder about BMW.
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Exactly!!
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On 03/14/2013 12:45 AM, Paul in Houston TX wrote:

If you have one of these cars an easy fix is if/when something like that fails, to splice in some fine-strand wire which will likely outlive the car. A good source for a DIYer is old Fluke leads; don't throw them out if you bend a probe!
As for door wiring, also a common failure on many vehicles... already had to repair the speaker wiring where it goes through the door jamb for my Jeep Cherokee as has just about every Cherokee owner. So this isn't just a BMW problem.
nate
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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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I would like to acquire some fine-strand wire but I do not have any old Fluke leads. Do you know where I can buy some? Thank you in advance for any help.
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My guess is that they are using a wire that isn't designed for high flexibility, in an application where high flexibility is important.
That looks like typical crappy automotive-grade vinyl and normal fairly coarse stranded wire.
It's breaking in the same spot because as the snorkel is moved in and out, most of the strees is at that one spot.
Considering that BMW has been famous for electrical problems since the Bavaria was new, this should not surprise you. --scott
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On 03/14/2013 7:15 AM, Scott Dorsey wrote:

Volvo 240 (1984 and other years) wagons had a similar problem with their tailgate wiring, where wires would always break in the hinge - the wiring was not unlike hinge wiring in laptops. It was a very tight routing which left only a small amount of wire that could flex with the result that after a few years stuff on the tailgate would stop working...
I solved the problem by moving the wiring outside the hinge and had it hang in a loop - not as nice looking, but never had any further problems. I kept that car for 25 years...
John :-#)#
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On 3/14/2013 12:41 PM, John Robertson wrote:

Laptops! Oy!
http://www.yellowjersey.org/photosfromthepast/HPCSUCKS.JPG
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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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