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

dpb wrote on Wed, 13 Mar 2013 20:15:16 -0500:

> What's the age of the vehicles and condition of insulation in the area?
All the vehicles are five to ten years old'ish.

> Are the vehicles in very cold or hot climates and not garaged by any
> chance where such degradation could have been accelerated by extremes?
The vehicles are all over the world. Same problem everywhere.

> Is there preferential failure in any given circuit(s)?

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===21AWG, 0.5mm2===20AWG, 0.75mm2===18AWG

> Perhaps a circuit operating at high capacity relative to wiring
> ampacity/insulation rating is aiding in the failure mechanism.

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

> What does BMW say?

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

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

"Arthur"

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

** Or use silicone coated wire and do it just once.



..... Phil

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

Phil Allison wrote on Thu, 14 Mar 2013 16:24:59 +1100:

> ** Or use silicone coated wire and do it just once.

Here's a picture of the loom, laid out (on a BMW E46 3-series):
http://www.bimmerfest.com/forums/att...4&d=1297298236

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

VinnyB wrote on Thu, 14 Mar 2013 05:24:43 -0500:

>>Replace the entire trunk wiring loom every five years.
>>BMW Part number: 61116907260
>
> What do they typically charge for such a replacement? Let me guess:
> $15,000 That makes sense. Anyone fool enough to by a BMW should be
> happy to pay for that fix.

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.