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E39 Electrical Problems Traced to Trunk Lid Harness Wire Chafing (DIY Diagnostic)

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345K views 236 replies 75 participants last post by  majeski2  
#1 · (Edited)
What do each of the 13 wires innervate in this E39 trunk lid wiring?

Is there a TIS on this apparently common wire-chafing problem?

The reason I ask:
- To improve our DIY procedure: Many of us have chafed or broken wires, which seem to enervate various lighting and latch components; many of us find out only because of weird trunk or lighting electrical problems; if we knew which components were innervated from this wiring harness, we could better build a DIY diagnosis of where to look for problems in the future!

EDIT: These electrical gremlins are known to be related to the trunk loom wiring harness:
- Trunk latch problems (not working, intermittent, weird behavior, etc.)
- License plate light problems (especially one and not the other)
- Trunk light problems (especially intermittent, fuse blown, or no power)
- Central Locking (ZV) system problems (of which there are many)
- Fuses blown related to the trunk latch, door locks, or tag lights

KNOWN LOOM WIRE CONNECTIONS:
01. Red/yellow line = 2 @ x712 -> trunk lid light (positive)
02. Red/black line = ?
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 = ?
NOTE: (majority color)/(line color)=(pin number)@(connector number -> description

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aliaw528 said:
My trunk lights stopped working last month, and i have always had some weird electrical gremlins. I read about this on Roadfly, check your wiring loom in the trunk where it exits out the hole. Looks like when the trunk lid is pushed to the fully open position (beyond 90 degrees), the wire loom gets cut on a deck lip because BMW made the wire loom too short. I fixed my broken wire with a connector (that was the trunk lights) wrapped each wire in elec tape, then put rubber bike tubing around that and elect taped again, then rolled the OEM boot on again. Next i need to put a rubber washer on the trunk lid deck lip. When fixing this, it is easier if you roll the rubber boot down.
Click to expand...
 

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#3 · (Edited)
z168 said:
1. how did you even begin to figure out that you had a problem there?
Click to expand...
It wasn't easy. Neither was it efficient.

I simply had weird electrical problems over the past 6 months of ...
a. Cluster suddenly reports "CHECK LICPLATE LIGHT" ...
b. Brand new 6418 13.5 volt 5 watt bulbs didn't light up ...
c. Trunk latch weirdly starts unlatching when I move the trunk ...
d. Wiggling just the scuba hose caused the trunk to latch & unlatch ...
e. Someone with the same problem posted their experience with the loom ...
f. Another E39 owner reported a cluster OBC error for years due to the same problem ...
g. Yet another E39 owner reported fuse #37, cluster lights, tag light, & taillight out due to this problem ...
h. Yet another E39 ... and another ... and another ... and another ... and another ... and another ...
i. Here is a Bimmerforums thread on this problem in the E39 ... and Roadfly ...
j. A nice set of pictures of the problem in an E39 is here ...
k. E39 Trunk Constantly Unlatches & E39 Dash Open indicator light & E39 Wires make me crazy

It seems to have taken months or years to find the real culprit for some (including me).

If we list what is affected by these 13 wires, and which fuses can blow, then we can help many others!

2. It might be a cheaper and far reliable to buy the harness from guys parting out
Click to expand...
I'm currently trying to figure out what the part number is for the harness.

It's either the cheaper well-named P/N 61116907260 "trunk lid harness" $215 USD + 10% tax ... or ...
It's the much more expensive poorly-named (if it's this) "trunk harness" P/N 61116936272 $1,708 USD + 10% tax (ouch)!

I'm hoping it's the cheaper two-hundred-dollar harness but I can't tell from the RealOEM diagram I posted whether it's harness #3 or harness #4.

Can someone help identify the part number & dozen items it affects?

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For cross reference, other BMW models with trunk loom chafing or broken wires were:
- E34 Wiring Frayed and another and another
- E36 Boot Wiring (more E36 boot wiring) plus E36 Frayed Trunk Wiring and more E36 trunk wiring problems
- E46 Trunk Lid Wires
 

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#4 ·
bluebee said:
What do each of the 13 wires innervate in this E39 trunk lid wiring?

Is there a TIS on this apparently common wire-chafing problem?

The reason I ask:
- To improve our DIY procedure: Many of us have chafed or broken wires, which seem to enervate various lighting and latch components; many of us find out only because of weird trunk or lighting electrical problems; if we knew which components were innervated from this wiring harness, we could better build a DIY diagnosis of where to look for problems in the future!
Image
Click to expand...
as for the pn 03 and 04 looks like certian yr. models.
now for the color wires. i hate to tell you this. but what i would do is hook up each wire one at a time. and see what comes on. if you unplug the wires to the latch it self and the plate lights, and try to pull the harness out, will be the fates way to elimnate what is what.
 
#5 · (Edited)
also i'm thinking the same as you for what controls what.
inside release, out side release, remote release, left and rt plate lights, alarm sensor, lock/unlock. that's pretty much all i can figure out, but what to what don't know.
you'll have to like i have posted, just take it all out. sorry you got to be the ginny pig on this one.
 
#6 · (Edited)
Here is yet another blue BMW that has the problem.

Note: Notice this blue BMW has two of the same wires busted as mine; I'll bet his right license
plate light was out of power (I think that's the red/yellow wire).

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#7 · (Edited)
honestly, the wires are going to the latch and to the plate lights. just unplugg it all, and slowly pull it all out. make sure there are on t like plastic clips that are taped to the harness that hold it to the trunk lid. just look around in there before you take it out, and as your pulling it out. once you have it fixed, and the wires back in place, i would zip tie the wires to the trunk lid. they are obiviously moveing as you open and close the trunk.



edit---doing body i can tell you this, takeing the wires out is a straight forward job. it is really easy to do. just make sure that the harness isn't tied down to the deck lid. the hardest part is making sure that you get the right wires back together. i would also recommend you takeing the latch out and the plate lights, so you can test the parts once you get the wires out, so for one you can see what does what, and you can make sure there are not problems. a tip, take a screw driver and manually latch the latch, so you can make sure it works.
 
#8 · (Edited)
In looking for the definitive DIY that pulls the harness out for repair or replacement (which I did not find) I did find this E36 DIY ... again with the same problem as we have on the E39 - and again - a BLUE BMW.

Why are only the blue-b's affected! :) I'm starting to feel a little superstitious ... only Blue B's have posted pictures on the Internet of the busted
trunk wires! :)

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#10 · (Edited)
lild said:
so are all these breaks in the wires located up and inside of the trunk lid or in the rubber hose?
Click to expand...
Hmmm... I didn't look before I pulled back the rubber hose. You have a good question.

Are the breaks due to the sharp edges of the trunk lid itself at the ends of the rubber hose or due to the stretching of the wires (in which case it might more often break near the centerline of the rubber hose).

Looking at the pictures again, it seems most of the breaks are in the same spot (within a couple of inches) in any one loom ... and it seems that most breaks are about a half a foot from the lid of the trunk. If it were mere fatigue bending and stretching, I'd have expected, somehow, the breaks to be centerline in the hose itself, but they seem to be further up, closer to the trunk. (Interestingly, all the pictures I've found are on Blue B's!).

What does that tell us?
Image
 
#11 ·
don't buy a blue bimmer. lol
i thought more about it last night. these wires should be able to bend without breaking into 2, plus some are still together, but have the wire scrape back. so my thinkin is this.
the wires must be staying in place. for exp. the wires are a certian length, but they are moving in and out of the rubber hose every time you close and open the trucnk lid. so they may be contiuneouly rub the inside of the deck lid, causeing the bare wire, and then breaking.
so we could do 2 things, one make the wires longer, or two, buy some plastic wire wraps that advance sells, (sorta like the rubber hose) wrap the wires (after splicing back together) and then reinsert the new wrap wires into the rubber hose.
 
#12 ·
lild said:
Don't buy a blue bimmer
Click to expand...
too late!

we could do 2 things, one make the wires longer, or two, buy some plastic wire wraps that advance sells
Click to expand...
Advance?

Is that http://www.advanceautoparts.com (877-ADV-ANCE)?

It's really really HARD to find anything on their shop-online site because they are just about the only sales web site on the planet without descriptions for their product (other than the name).

Is this what you're referring to?
Dorman Electrical - Wiring Accessories

Part No. 85266

http://shop.advanceautoparts.com/we...product_Electrical---Wiring-Accessories-Dorman_25984907-P_N3067C_A|GRP2020A____
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#14 ·
bmw_n00b13 said:
Nothing in the TIS that I can find, but I only figured out how to install it just this morning….
Click to expand...
Drat! It would really be nice to have the 13 (or so) components listed which that problematic trunk loom connects to.

If we had that definitive list, we could point folks with related electrical oddities to the trunk lid wiring harness for DIY debugging.

I really wish I could find my second Bentley to see if the wiring diagrams there offer any light as to the purpose of the 13 wires!

01. Red/yellow stripe = ? (possibly right license plate light)
02. Red/black stripe = ?
03. Gray/yellow stripe = ? (possibly trunk un-latch electronics)
04. Gray/brown stripe = ?
05. Gray/brown stripe = ?
06. Gray/black stripe = ?
07. Gray/green stripe = ?
08. White/brown stripe = ?
09. Brown = ? (possibly right license plate light)
10. Brown = ?
11. Brown = ?
12. Brown = ? (possibly trunk un-latch electronics)
13. Brown/blue stripe = ? (possibly trunk un-latch electronics)
 
#15 · (Edited)

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#16 · (Edited)
I'm still looking for what problems to tell others to look out for. Here's one case of lights flickering as the trunk was raised and lowered (similar to my situation of trunk lock actuating as the trunk was raised and lowered).

See this enticingly short explanation of what causes the problem here ...

"The insulation starts cracking where the wire flexes - and eventually things start misbehaving."

The question is still the same: What "things" can misbehave?
- Trunk latch
- License plate light
- ??? (what else)???

Image
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#19 · (Edited)
"The insulation cracks where the wire flexes - and eventually things break.

In digging s'more, I found this trunk-lid related electrical-problems thread which implies additional components might be associated with the 13 wires in the trunk lid loom:

That makes the potential suspect list the following (so far).
- trunk wired cabin unlock button ?
- trunk key remote unlock switch ?
- trunk lid latch (known)
- left license plate light (known)
- right license plate light (known)
- left backup light ?
- right backup light ?
- left inside trunk light ?
- right inside trunk light ?
- trunk alarm ?
- ???

What else electrical is inside the trunk lid?

Image
 

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#20 · (Edited)
bluebee said:
Here is the updated list of 13 things that may go haywire if/when your trunk loom wire insulation begins to crack from repeated flexing
Click to expand...
Based on this description kindly supplied by ganesht, here's what we have so far:

01. Red/yellow stripe = 2 @ x712 -> trunk lid light (positive)
02. Red/black stripe = ?
03. Gray/yellow stripe = trunk latch electronics
04. Gray/brown stripe = 2 @ 709 -> left license plate light (positive)
05. Gray/brown stripe = 2 @ x709 -> left license plate light (positive)
06. Gray/black stripe = 2 @ x710 -> right license plate light (positive)
07. Gray/green stripe = 3 @ x1377 -> trunk lid locking switch
08. White/brown stripe = 1 @ x712 -> trunk lid light ground
09. Brown = 1 @ x709 -> left license plate light (ground)
10. Brown = 1 @ x710 -> right license plate light (ground)
11. Brown = 1 @ x1377 -> trunk lid locking switch (ground)
12. Brown = ?
13. Brown/blue stripe = ?

Can someone check to see if we're right?
And, what are the missing descriptions?

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C
#24 · (Edited)
Gotta go and check mine over the weekend. My theory based on all these pictures and the location is that it is a combination of chaffing and stretching due to the angle at which the wires pass through the grommet. I also think that over time the rubber grommet dries up and hardens up over time increasing the transfer of friction to the wires themselves.

For those good with a soldering iron, I would splice and solder back the sheared or broken wires, re-wrap with electrical tape and put a split wire loom or spiral around the harness (space permitting) to protect it from future damage. Also would suggest replacing the dried out grommet with a softer newer one to minimize future damage. If there is enough slack in the harness, I would also pull/push the harness about 2" so that at least an area that was not previously at the bend/chaffing area is now at the bend. My theory is that this happened over a 5-10 year period so a "new area" might take that long before the wires get worn out again. I'll report back my finding over the weekend.

Here's a link to what split loom wire harnesses look like. For this application, I'd probably go with the first one-spiral wrap, both of which you can probably find at your local Radio shack or off ebay. Split loom/spiral wraps. All you need is about 6" worth of it for this.
 
#26 ·
dvsgene said:
I would splice and solder back the sheared or broken wires, re-wrap with electrical tape and put a split wire loom or spiral around the harness (space permitting) to protect it from future damage.
Click to expand...
We definitely need a good DIY repair fix for multiple broken wires.

Of course, the "right" way would be to buy a whole new loom but it seems nobody does this. Every dealership I checked says they never sell it (they couldn't even tell me which loom it is in the realoem diagram above).

Most people splice and wrap the wires.

The suggestion to make 'em longer would work, but, only if we do ALL 13 wires.

So, it will be nice to see pictures of other people's results. I still have mine just wrapped with electrical tape ... I'm waiting for all the good fixit suggestions to come in! :)
 
C
#28 ·
Doru, I think that's a good idea but some grease or lubrication can eat away at rubber or if it begins to seep into the electrical tape the adhesive of the tape unravels which is why is suggested replacing the grommet with a new one. I'm sure it's less than $5 even at the dealer. Follow that with the split loom to protect the wires and it should be good.
 
#29 ·
I had to lengthen the cut wires....

After my 1st initial repair didn't hold (I didn't solder broken connections, I didn't lengthen wires), my Uncle and I spent 2 hours putting and soldering in extensions and re-wrapping the loom. It has been fine for about 2 mos. now, but I will check it later this week for evidence of cutting to the wires that were not lenghtened and report back. If you are buying a new harness, I would check and see if the total length is longer than stock. If not, then you will run into the same issues in time. It really seems they didn't provide enough length. Maybe there was a change in the trunk hinge design after the wiring length was deteremined? Because it really seems it is the last inch or so when opening the deck lid past 90 degrees that causes the stress.
 
#30 ·
aliaw528 said:
After my 1st initial repair didn't hold (I didn't solder broken connections, I didn't lengthen wires), my Uncle and I spent 2 hours putting and soldering in extensions and re-wrapping the loom. It has been fine for about 2 mos. now, but I will check it later this week for evidence of cutting to the wires that were not lenghtened and report back. If you are buying a new harness, I would check and see if the total length is longer than stock. If not, then you will run into the same issues in time. It really seems they didn't provide enough length. Maybe there was a change in the trunk hinge design after the wiring length was deteremined? Because it really seems it is the last inch or so when opening the deck lid past 90 degrees that causes the stress.
Click to expand...
Maybe the fix is to add 3-4 inches/wire then? (solder, and wrap each one, then back in the grommet?)
 
#32 ·
For the cross-reference record, here is another suggestion as to how to fix the trunk loom without actually replacing the entire loom itself:

"... my dad used to run a TV/radio repair shop, and he did this a few times when fixing broken wires: He would solder the wire back together, then lay the repair lengthwise on a piece of black electrical tape. He would then put some 5-minute epoxy on the repair, and wrap the tape around the glued area like a cylinder. After the glue had dried, he would wrap it with electrical tape again. It worked great, but was somewhat inflexible. In this application, that could lead to problems down the line.

I have been thinking about doing the same, except instead of epoxy, using RTV, and using shrinkwrap instead of electrical tape. This would be somewhat flexible, protected from he elements, and quite strong."

The quote above is from Philboski in the electrical gremlins thread here.
 
#33 ·
Looks like we can add "battery drain" issues (not otherwise related to the FSU) to the list of electrical gremlins that might point to frayed or broken trunk lid loom harness wires ...

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#34 ·
trunk wire harness is a nightmare

this has caused me so many more issues than listed! i did have the harness repaired under warranty at the dealership and 2years later the same thing only they said it wasnt covered because the car was out of warranty and their work was only covered for a year, idk! they offered to replace the entire harness for around $500! its crazy that after two years to have the same prob again. they told me that bmw only alows them to splice new wires and not replace the entire harness! but i do know why it happened on my car atleast, its that the harness folds and gets pinched every time the trunk gets closed. i never put two in two together when i would see the little black rubber sticking out of the trunk lid and just thought it to be a rubber lining or seal on the trunk or window seal! one day it was bugging me and i looked further into it and realized it was the harness! so i removed the rubber boot pulled it down to expose the wires and they were all cracked except for one wire and one was completely separated , this would explain why my trunk would not open with the key or the button inside the car and the trunk lights didnt work and the alarm wouldnt beep when set and the alarm would always go off for no reason and the battery would suddenly be dead for no apparant reason and the central lock would sometimes not work and the licence plate light would sometimes stay on when the car was off and the trunk could only be opened with the key, hmmm! what else im sure there is more! so basically after finding this out and taking it back to the dealer and having them tell me that it wasnt covered and it would be $500 i decided to rewire it the best i could! i spliced and reconnected the wires and taped them real good and right away the trunk worked and all my probs were fixed, so i thought! now about one month later its starting all over again, i havent looked at the wires but im sure they are coming undone or something!! evrything is fine except the battery issues! my car just randomly has a drained battery, for no reason its just dead after i drive it all day with no probs. does anyone know if this could be causing the battery drain or shorting it out or does the car have a theft protection where the battery disarms the car from starting! it will start from a jump everytime and the battery was replaced two years ago! evrything checks out fine as far as the alternator goes! can a cracked windshield set the alarm off? any help or suggestions would be great! i love this car and it drives great just some minor issues!
 
W
#39 · (Edited)
http://www.bimmerfest.com/forums/showpost.php?p=3208773&postcount=12

I had this same problem when I bought the wife's car 2 years ago I came out to a dead battery 2x, the trunk would open when I turned on headlights :dunno: and lights would flicker in car/glovebox, speed/key in the ignition chime worked sometimes. once while opening trunk chime kicked in then when I closed it stopped so I reached for the harness and BAM frayed wiring...guess what, her car is TOPAZ like so many others...hmmmmm

rewrapped all the wires individually with electrical tape and then rewrapped the the whole bundle then slipped boot back over...no probs since(yet). The position of boot is very bad and I even pointed it out to seller of car when it was bought, because I could not understand why the harness was so visible with trunk closed
 
C
#41 ·
Just checked my trunk harness and repaired 1 wire. I was getting a "trunklid open" message, and prior to that every once in a while the parking lights would flash continuously after disarming the alarm. When that happened it was like the someone pressed the hazard lights.

My E36 had this problem prior to my owning it and was repaired by the dealer for some ungodly sum of money...
 
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