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

Sorry if I posted this in wrong location,seen many of your posts and like what I saw,thought you could give me answer to my nightmare.
I took my 2000 528i e39 BMW to dealer, can not read obd2
or other diagnostic plug,they gave me a hefty bill of what would cost to replace
cluster and code it to Vin and then see if that resolves reader issue.
The car runs and drives like a bimmer, issue I have non working gas gauge,speedometer,rpm,Temp and picxil displays.
The only lights come on when key is turned are the
ABS, Seat-belt,oil,battery and illumination of cluster when lights are on.

Other issue I have too that I don't know if related is the BMW key with sensor is broken and doors can only be opened by inserting key,the radio goes off by itself constantly,
on-board navigation always on and no display ,the front seat heater buttons
do not come on and does not give heat.
Please help repair issue,and point me to links to resolve issue.
Thanks in advance.

I checked sun-visor works fine and no interference with cluster
or any electronics,all buttons on steering wheel work fine
including cruise control.
I checked all fuses all OK, is there a main inline fuse under seats somewhere
that could be culprit of issue.
I also checked the BMW ABS w/ DSC Hydro Module E39 under hood and it has
yellow numbers on it like it was bought at a salvage yard and replaced.
so I don't know if it was paired to vehicle .

Help, please... My 2001 540i Touring displays the "Trunk lid open" warning light, even when the trunk lid is locked. I checked the two wiring harnesses that come from the roof of the wagon into the trunk lid and all wires seem to be good--no fraying or broken wires as far as I can see anywhere in any wires. I was prepared to fix any frayed or broken wires, after reading several great posts that led me to think this would be the source of the problem. But it's not....so, any other good ideas? I appreciate any and all thoughts. With best wishes, Doug in Plattsburgh, NY....

There is a very nice E39 trunk harness repair DIY referenced in this thread today:
> E39 (1997 - 2003) > Electrical problem - trunk unlock & trunk lights

Specifically, the attached PDF:

Originally Posted by Domer1982

- BMW 528i Trunk Harness Repair.pdf (google docs)
- BMW 528i Trunk Harness Repair.pdf (pdf)

Reproduced below for posterity.
PS: Anyone notice that it's yet another blue bimmer?

great thread, i had the same problem yesterday, the right licence plate light, thanks to this thread, i found the Gray/Black wire broken and so many others cracked, fixed the broken one and i will make all of them as in the pdf.
BlueBee ..thank you

Originally Posted by bimmerteck

I wrap harnesses prone to breakage snugly with a stout friction tape after repair, it forces them to flex as a bundle and eliminates the stress falling on a single point which will fail sooner.

Fantastic tip on the friction tape sir! just fixed my cables tonight thanks to this thread! working license plate lights! I fixed a broken cable and prepped the ones that were about to break, and then re-wrapped the whole area with the friction tape, good stuff!

Originally Posted by bluebee

...As for the red/black; I'm not sure why the EE's out there can't tell us where it goes yet!

Originally Posted by fortunateson

... Could the red/black (El Diablo) wire be for the release just above the lisence plate?

Sorry to bring back an old thread.

I found the insulation on the red/black wire broken. After reading through this thread, I realized that no one has identified the component to which the red/black wire connects.

After digging through Bentley manual, I found the RT/SW wire connects Fuse 53 to S167, which is described as the "Lift gate lock switch". This is on diagram ELE-827. On page 610-19, S167 is described as the "Tailgate lock (central locking)" located "In tailgate latch".

Also on diagram ELE-827 is the "Trunk lid locking switch", S117. This is described as the "Trunk lid lock switch" located on the "Underside of trunk lid, near license plate". I think this is the switch that you press to unlatch the trunk lid if it is unlocked.

I think the red/black wire supplies power to the switch operated by the remote or the key in the cylinder.

Originally Posted by Steve530

Sorry to bring back an old thread.

This thread is intended to be canonical ... for trunk wiring loom diagnostics ... so ... you're "supposed" to bring the thread back whenever there is new information!

Originally Posted by Steve530

I realized that no one has identified the component to which the red/black wire connects.

The original intent of this thread was to understand what 'could' happen if any one of the wires broke - so - I agree - it's important to figure out where ALL the wires go!

Originally Posted by Steve530

the red/black wire supplies power to the switch operated by the remote or the key in the cylinder.

Aha! Now we have a better handle of what symptoms could point to that wire being broken!

How does this update look?

Bluebee that's hilarious! Good work though.
My story- 2001 330ci convertible. Trunk would not open- key or interior button, had to stick key in lock. Dealer wanted to sell me a new general module for $800. I read on the forum about wiring loom issues, but was apprehensive about cutting it open. Went on a road trip to Moab UT. Driving around Arches with top down, 30th wedding anniversary- guess what- yes, top would not go up. Rain coming in... panic- drive home 5 hours in rain?? Remembered forum.. found a garage open @ 4:30 Friday night on Labor Day weekend- while wife called, I slit snorkel open, found 10 of 13 wires broken- garage fixed in 30 minutes for $80. All fine now. Told dealer eventually, who never heard of the issue with loom. Ps car is BLACK.

Yet another trunk wiring loom - this one with weird results due to a previous 'repair':

Originally Posted by FLE39

The "check license plate bulb" warning light has been on since I bought the car. Both lights worked which I found odd. My trunk actuator has not worked either.

So I took the harness out of the trunk and back to the trunk near the battery.

I didn't disconnect it from the car... but I had it back to the foam bushing in the trunk area. Laid it out in the trunk and out the bumper. I had 3 broken wires.

The PO taped the hot from the working left light make the right plate bulb work. So both bulbs worked, but the computer saw a dead bulb still.

So I removed that blue taping clip.

Soldered the 3 broken wires back together with extra wire. Used electrical tape and wrapped the whole thing and each branch.

What I found was the way it comes from the factory the harness was attached to the boot in certain spots so it wouldn't allow movement. so now the trunk rubber boot is not attached to the wires.

It's now truly a through conduit. so everything has plenty of slack and ability to move unlike the stupid design from the factory.

If they did not anchor the boot to the harness I doubt any damage would have occurred. and the factory wrap was a joke.

A full loom/wrap is needed. I removed all of the factory wrap/sock/jacket. I think the tightlightly wrapped electrical tape provides good movement and protection. I'm happy Good professional fix. No bulb warnings and my trunk actuator works!

It took me 2hrs and just the cost of the elecrical tape and heat shrink... so if you have it, most of us do... $0 fix.

Now, I need to see if AutoHaus will accept my trunk actuator return. I work out of town and am only home on weekends so when I do projects I like to have all parts for a worst case scenario. I never even opened the thing.... but it's an electrical part. I will see if they will take it back or not. 10 or 20% restock would be ok with me.

Originally Posted by fortunateson

Could you explain exactly how you loosened yours.

Originally Posted by FLE39

Took me about 5 minutes to get the harness out.
1. Open trunk,
2. Remove liner of the trunk lid.
3. Open the battery access door.
4. Back feed the harness (which comes with the boot) into the trunk.
'5. Then remove all the crappy OEM wrap and go to work.

I slid the boot up and down as I worked. (Remember, now the boot moves freely from the harness).
It's not a very hard job at all.
I recomend removing all the factory BS jacketing and how the boot is tethered to the harness via a wrap. Use heat shrink and extras wire to repair the broken wires. electrical tape back in a nice tight wrap.

Originally Posted by fortunateson

I couldn't figure out where the hell the wires went after they disappeared front the trunk. I thought they went into the cabin.

Originally Posted by FLE39

The harness goes from the trunk lid through the rubber boot into the body, which you can see where it comes into the body via opening the battery door and the side carpet.

Up toward the shock tower area you see the harness coming into the trunk (body) section. That foam deal is in the trunk, and it's as far as I chased the harness. It's the separator from the trunk and the passenger side of the cargo wall. Tightly means you wrap regular electrical tape TIGHTLY. as in tighten your grip. Wrap should be at a 45 degree pattern with slight overlap and cover 100% of the wires. I used 3M Tape, b/c it's what Home depot had. You will burn up quite a bit of tape. Make sure you have a roll that is almost new. And then wrap each leg coming off; ie one leg for each license plate fixture, trunk light and lock cylinder. should look like a factory harness when you're done. Just done properly opposed to the crappy job BMW did. Most Jap cars have their harnesses wrapped like I did from the factory. It works and lasts a long time if done right. I don't foresee ever going back into the trunk unless the actuator goes out or someone jacks the cylinder with a screw driver. speaking of which, I almost didn't plug the lock cylinder back in. So if someone did use a screw driver it wouldn't disarm the alarm and it would go off. Just a thought. I mean... yeah, if you use your key yes it disarms it. if you use a screw driver to totally f the thing up it still turns the switch and disarms it. Not a very high tech deal there. That's how Ford Super Duty's get jacked all the time. The alarm doesn't even go off. 80's technology. sorry for the side-track, but it's right there when you're doing this. .

EDIT:
Yet another repair was recently reported:

Originally Posted by figjam911

I did mine after the license plate lights check light came on...yes, I found a broken earth/ground brown wire in the loom between the body and the trunk/boot lid. Just peel back the cables slowly to expose all of the cables after removing the inner lining above the battery. Then you'll have enough room to cut the cable and join them by just removing 1/2 " of cable each end after cutting and twisting together. Before you do that, just slide on some shrink sleeve and heat it with a cigarette lighter...bingo...all fixed.

I had 1 broken wire in the loom...4 other nearly broken through and 3 or so others with crack in the insulation. So I repaired the lot by cutting and and splicing and sealing with shrink sleeve.

Cost me $7 only for the sleeve. That's all...no soldering. Took about 2 hours.

I got the issue too.. Actually this is my second time with the same issue. Over ago had this issue the first time. I fixed the issue by soldering the broken wires together and using heat shrink. Now one of those wires has broken again, about 1/3 inch away from the previous spot.

I'm going to solder that wire again and fix this better in summer. I'm planning on replacing about a feet or so of the original wiring to solve this issue for good. I'm thinking about using silicon wire instead of pcv. It should hold up better to continuous bending.

Thank you bluebee for gathering all the info!

Since the wire thickness weren't clearly stated I did some digging in WDS and made a minor update:



Now I can order the correct size wires for this fix.

Originally Posted by HTK12

Now I can order the correct size wires for this fix.

Now that is interesting that the wire thicknesses are NOT the same for every wire in the trunk harness!

Originally Posted by shaftdrive

Now that is interesting that the wire thicknesses are NOT the same for every wire in the trunk harness!

Huh? It would be interesting if they were. Car manufacturers try to loose as much weight as possible and one good place to do it is the wiring. Different components in car require different currents hence the different wire thickness.

Just wanted to thank all those who have worked this before. I could only open the trunk lid on my '99 528i with the remote. Google sent me here, and I found a broken wire (Gray/Yellow) in the same place inside the flex boot. After soldering it up, the latch and interior switch are now working again. Now I've signed on to the sight. What a great resource.

As a remark, there "might" be 2 causes, sometimes combined, sometimes independent that lead to frayed wires in the loom. Look at bluebees picture:



In this pic, they all break in the same spot. Also, I notice that my wire loom might sit different than any other ones that failed - at least as per pictures. I will post later a pic of mine, which hasn't failed (yet, and I hope never).
My loom, when the trunk lid is closed sits to the left of the trunk strut in a way it doesn't touch it. Guaranteed. How do I know? The snorkel dug in time its resting "bed", visible by the eaten paint in that particular spot. It sits far apart from the strut. Any closer to the right, and will interfere, and maybe that's why some wires are chafed in the same spot. Maybe the snorkel is not positioned correct. Maybe in some cars it was preloaded, in some not. I know since this wiring loom chafing started, I looked how the snorkel will bend when I close the trunklid. Mine starts flexing, the bending towards opening of the trunk, then it gets pushed to the left of channel where the trunk strut is (trunk strut to the right), leaving a space between it and the strut.
The other issue might be how the harness itself is positioned inside the boot lid, i.e. how much slack is left in the harness before entering the snorkel from the boot. To little, and the wires are in tension when the lid is fully opened. And I think the "slack" is minimal, something of the order of 1/4" or maybe 1/2".
I will post a pic tonight of what I tried to describe above - it should be visible, although I used the touch-up paint in that place. Again: no failed wiring loom exhibited the pattern I see on my car.
Maybe I am right maybe I am wrong, but just thought to throw it out there, I might even have to try to make a short vid on how that snorkel collapses in that place, so whoever tries fixing the loom, maybe can find the "correct" position of that rubber, if a correct position indeed exists.


OK. I'm home and took the pics, and I will try to upload the short vid (which isn't very clear unfortunately, but hopefully you can see what's going on together with the 2 pics).

Here is the latest on the trunk loom summary:
NOTE: We need to identify the respective AWG of the following 13 wires (0.35 mm2===21 AWG, 0.5 mm2===20 AWG, 0.75 mm2===18 AWG)

BMW E39 Trunk Wiring Loom, BMW Part number: 61116907260
01. Red/Yellow stripe => pin 2 @ x712 === trunk lid light (positive)
02. Red/Black stripe => pin 1 @ x1191 === Rear lid lock switch (positive)
03. Gray/Yellow stripe => pin 3 @ x1377 === tunk lid locking switch (open signal)
04. Brown/Gray stripe => pin 2 @ x709 === left license plate light (positive)
05. Gray/Brown stripe => pin 4 @ x311 === zv drive (lid closed)
06. Gray/Black stripe => pin 2 @ x710 === right license plate light (positive)
07. Gray/Green stripe => pin 4 @ x311 === zv drive rear lid (positive)
08. White/Brown stripe => pin 3 @ x311 === ZV to luggage compartment light
09. Brown => pin 1 @ x709 === left license plate light (ground)
10. Brown => pin 1 @ x710 === right license plate light (ground)
11. Brown => pin 5 @ x311 === zv drive (ground)
12. Brown => pin 1 @ x1377 === trunk lid locking switch (open signal)
13. Brown/Blue stripe => pin 2 @ x1191 === Rear lid lock switch (unlock)
NOTE: majority color/line color=> pin number @ connector number === description (details)

See also these which were posted in a thread today:

Originally Posted by moosewks

Hi all,
again i thought i would "give back to the forum" as this topic is found many places, but my "chronics" turned to "broke".. only then, could it be resolved..

Problem 1: BMW (E39) battery is dead in 3-4 days if left sitting undisturbed at the curb..

Problem 2: BMW (E39) siren sounds at ~230am after 6 months using a new battery.. vehicle unable to unlock, lock, or operate anything other than the siren for the neighbors benefit.

Problem 3: BMW (E39) does not go to sleep after 16 minutes idle time.

Special note: after the car living at the Stealer for 2-weeks of power drain tests, the best they could come up with was a speculative faulty blower fan resistor (Not the Problem!!!)

Final Problem: Trunk lock cycles wildly when trunk hatch open and lifted upright, and license plate lights dead..

FOUND: In the Trunk wiring boot (that harness that leads from the chassis body to the trunk hatch was twisted and chafing to where the wires are cracked and shorting out (hence trunk lock issue and lic plate lights dead).. One would never see it unless it was removed for inspection..

Solution: since a new wiring harness is cheap and labor installating it is $500+++ due to the chassis installation route under rear seat, purchase new harness for trunk hatch and spliced it into the existing wiring into the chassis.. No my car sleeps soundly, and operates after 2+ weeks of curb time.. This issue is now Solved..

Originally Posted by moosewks

This power drain issue developed over time (~4 years)..

During that period,
i had batteries charged with a spare in the trunk in case
i was stranded (a realized event)....

In the final year before resolution, i pro-actively swapped batteries every 5 days..
The power drain became so aggressive that even if the car was operated, it may short and die on the road (discovered this exactly 99mi West of Phoenix, AZ with the horny toads...This is a thrill at 90mph @ 4pm..)

I am convinced the wiring harness factory installation is what lead to the wire bundle being stressed, and insulation cracked and severely degraded... the wires were shorting out intermittently and simulated a "trunk lite on" when things were good, and a dead short to ground at worst case.. Finding the problem was the matter..

"we had to destroy the village so we can save it"... So to, i had to develop the problem so i could fix it. All this sorrow, and i am still married... Thanks to my loving wife for your patience, and wasn't that a wonderful Arizona sunset while waiting for AAA wasn't it?

For the record, folks on the E46 side have been trying to order the complete wiring harness for the trunk loom, and have been stymied by lack of information.

Details below:

Originally Posted by bluebee

I see you have an answer from the expert already - but - if it helps, we've on the E39 side determined the gauge of all the wires, which you'll find in this thread. I don't know if the E46 gauge is the same - but - the PROCESS we used to determine it should be the same.
- How to diagnose & repair cracked, broken, or frayed BMW trunk loom wires causing all sorts of strange mischief (1)



There is a recent healthy discussion of what material to use for the BMW trunk loom in the alt.autos.bmw USENET nntp newsgroup, which you can find over here:
- What is the root of this BMW design flaw in all 3,5,7 series BMW trunk wiring looms?

Note: Google stinks as a nntp newsreader - but I give the Google Groups link because some of you might not have an NNTP protocol client installed.

EDIT: (didn't see this when I had posted above)


Most of the time, when I call the stealer, the data matches - but - for some whacko odd reason, all the answers I received from calling MULTIPLE dealers on the trunk wiring loom make no logical sense.
You would think that the dealer would be VERY FAMILIAR with the trunk wiring loom part number - since a LOT of people MUST be going to the dealer to get their strange electrical symptoms fixed - and I can't imagine that the dealer is manually splicing wires like we do.
So, logically, there must be a LOT of trunk looms being replaced, right?

Guess what? I called BMW of San Jose, BMW of Mountainview, and BMW of Fremont (my three closest dealers), and NONE said it was a commonly replaced part. In fact, none had the wiring loom in stock. And, all professed total ignorance of anyone ever ordering a replacement loom.

This makes no logical sense, I agree. So, anything you can find out by calling the dealer, and reporting back, would be useful information for both the E46 and E39 teams!