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

322K 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


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.
 

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#114 ·
Good news Bluebee! I have a TITANIUM SILVER 98 M62 with chaffed wires at the deck lid grommet.
Started with apparent actuator failure. Replaced actuator but no improvement. After several minutes of chin rubbing pulled down the grommet and sure enough: 2 chaffed wires. Repaired with crimp connectors & shrink tube, original actuator works fine.
Now have 'check rear lights' on the dash, but no lights are out. Probably same problem, I'll look this weekend.
 
#115 ·
Bugger... three broken wires!Grey/green, brown, and the mysterious red/black. Tried to remove the snorkel tube from main body so I could slide it past the breaks for a nice clean repair but it won't disengage. I wonder where it it secure near the rear seat? I may go to a local wrecking yard and see if the have a good harness with no breaks but I would still have to dis-engage the harness from the body; any ideas? This repair is some-what minor but good gawd doesn't BMW hire engineers with degrees?!!! So what does the red/black wire connect to? PS Thanks Bluebee for all the work you do on this forum. (And my car is a '02 525i in Steel Blue!)
 
#116 ·
Tried to remove the snorkel tube from main body so I could slide it past the breaks for a nice clean repair but it won't disengage. I wonder where it it secure near the rear seat?
That's interesting. Most people pull the snorkel down from the trunk lid side; so I can't tell you how to remove it from the body side. Let us know (with pictures if you can) how that works out.

If others have removed the snorkel from the body side, please let us know what the procedure is, so all benefit.

I would still have to dis-engage the harness from the body; any ideas?
I think it was G.P. Burdell, who, on his E46, did just that. He removed the harness and repaired it off the car. Then re-installed it. His DIY is referenced. If you go that route, please SNAP PICTURES as I haven't found yet an E39 who removed the $200 harness.

what does the red/black wire connect to?
Good question!

If anyone knows what the red/black wire connects to, please let us know!

my car is a '02 525i in Steel Blue!
Mine too! Those blue B's sure do seem to be badly afflicted by this trunk-loom BMW design flaw!
 
#117 ·
Didn't call the dealer yet but the wrecking yard guy said that the trunk harness could only be separated from the main harness but cutting it. I told him that BMW lists a trunk harness as a separate part but he insisted that there is no plug/ connector to disengage and that I would have to splice the new harness into the main harness. If that's true the why would anyone pay $200 to splice when you may as well repair the original? I like the idea of wrapping all the wires with friction tape (NOT electrical tape) in an effort to build in some rigidity to all the wires in an attempt to prevent a repeat of this anoying problem. RED / BLACK, RED/ BLACK?!!! Aren't these colours associated with Lucifer and his boys?
 
#118 ·
I told him that BMW lists a trunk harness as a separate part but he insisted that there is no plug/ connector to disengage
It is definitely listed as a separate harness; so, I 'assume' there is a connection.

The G.P. Burdell DIY might have that connection described.

As for the red/black; I'm not sure why the EE's out there can't tell us where it goes yet!
 
#156 ·
...As for the red/black; I'm not sure why the EE's out there can't tell us where it goes yet!
... 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.
 
#121 · (Edited)
Just for the record, my horrid wiring loom repair job is looking more and more embarrassingly bad.

Every time I open the trunk, I shudder at what it is starting to look like; but at least all the buttons work to open the trunk! :)

 

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#122 ·
[quote=bluebee;6313654]Just for the record, my horrid wiring loom repair job is looking more and more like what the BMW engineers designed, over time.

Every time I open the trunk, I shudder at what it is starting to look like; but at least all the buttons work to open the trunk! :)

[/quote]

OMG!!!!! There must be a way to do it "nicer"!!!!
 
#124 ·
[quote=bluebee;6313654]Just for the record, my horrid wiring loom repair job is looking more and more like what the BMW engineers designed, over time.

Every time I open the trunk, I shudder at what it is starting to look like; but at least all the buttons work to open the trunk! :)



OMG!!!!! There must be a way to do it "nicer"!!!![/QUOTE]

:rofl: did you do it in the dark????
 
#125 · (Edited)
Called the dealer just now. There is not a junction where the trunk harness plugs into the main harness. The sub hareness that you can purchase needs to be spliced and soldered in at nearly the same location where the breaks occur. (why bother; repair the original one.) There is no way to dis-connect the bellows/ snorkel in order to slide it past they are so you can make an elegant repair and not have to cut the rubber tube. I'm thinking that I'll go down to the local wrecking yard and see where the harness sits near the package shelf. I may be able to determine if the bellow/ snorkel could be detatched further up-stream. I may find a section of the harness that I could buy and replace it within the cabin itself rather than hacking up the bellow/ snorkel. Service tech says that this is a very common problem and happens on 3 series as well. Could the red/black (El Diablo) wire be for the release just above the lisence plate?
 
#129 ·

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#130 ·
Trunk lid wiring harness issue

Responding to an old post- 2001 330CI- first the dash display told me the tail lights were out, but they were fine. Annoyance. Then the key could no longer unlock the trunk- had to actually stick it in and turn it. More annoyance. Tried reprogramming the key, no luck. Finally took it to the dealer, who said I need a new GM for $900 +. Not quite that annoyed. Plus, didn't believe them- all other locks working, except trunk (which would not work from under dash button too. Replaced trunk lid actuator- no help.
Then on a trip 8 hours from home, noticed the top would only go up or down if I got out, manually opened the trunk and closed it. Weird. Assumed it was Saxon devil gods getting revenge. Should have been a clue. Then top refused to go up at all. Stuck in cold November evening, rain forecast, 8 hours from home with top down on 29th anniversary trip. Remembered blog posts about harness, and finally opened up harness (no longer annoyance, now a PROBLEM). Wife shrieking. 10 of 13 wires were BROKEN. Found a shop open at 4:30 Veteran's Day Friday night, got all spliced and taped up. Cost $80. Now top works, key opens remotely, dash lights no longer give faulty reading. CHEAP FIX, if having similar trouble TRY IT.
Also, harness had been identically repaired before, about 2" away from new breaks. BMW SHOULD HAVE DONE A RECALL ON THIS! Thanks, BMW blog forum!!:):)
 
#131 ·
(no longer annoyance, now a PROBLEM). ...10 of 13 wires were BROKEN
We are glad this thread helped. That's why it was written! Especially since the problems are varied (depending on which of the wires are shorting out or opening up).

Would you kindly give back to the team and post a photo of your repair?

BMW SHOULD HAVE DONE A RECALL ON THIS!
It's our fault. Not BMWs.

When I looked up the recall records for my model year 525i, there were only 25 reports in the NHTSA database!

- How to report a BMW safety problem to the National Highway Traffic & Safety Administration for a product recall (1) and what E39 safety repair problems have already been reported to the NHTSA (1) & BMW E39 ignition coil recall information (1) & the safercar.gov recall search engine (1) & how to find out if your BMW E39 is involved in a recall (1) (2) (3) (4)

If we want a recall, we should report it to the NHTSA first!
 
#132 · (Edited)
This is my first post on here, but first off I'd like to say thanks to bluebee and many others on here for the wealth of E39 info that helped me before my purchase and since. Up until 2 weeks ago I had only owned E36 M3s as far as BMWs went, and ended up buying a 2003 530i Sport with 63k miles on it from a local dealer. The car is immaculate inside and out (titanium grey/black), but started giving me problems the day after I purchased it. Turns out the alternator went out, which I replaced myself that weekend.

Since then, I've had a few electrical annoyances, which I'll list here:
-front windows automatically opening (sometimes just an inch, sometimes up to 6 inches, has happened 7 or 8 times, usually in crowded downtown areas)
-trunk automatically popping open
-will be driving along, with either the fog lamps or high beams on, and the indicator for either one will go out in the dash, but the lights (fogs/highs) will still remain on. Turning the switch off and on again fixes the issue until the next time it happens, which is seemingly random.
-when I purchased the car, all three brake lights worked just fine. Within the last 2 days, I have lost the third brake light (though the socket and bulb filament are fine), and the left brake light (haven't checked this bulb yet)

I have pulled back the rubber loom and some of the tape on the trunk wiring harness and it all looks fine (this was a quick glance in 20 degree weather). I have had some fraying issues with the trunk harness on my E36s, but the issues weren't as erratic (probably because the E36 is a much simpler car electronically). One of my friends that is familiar with E39s is saying my issues sound like either the Body Control Module, or the Light Control Module. Any input would be greatly appreciated.
 
#134 ·
front windows automatically opening
If it's all the windows, it could be the key in your pocket is being activated by pressing against the buttons?

trunk automatically popping open
This thread.

lost the third brake light (though the socket and bulb filament are fine), and the left brake light (haven't checked this bulb yet)
Left brake light is usually corroded connections. Doublecheck that the center brake light isn't the socket melting.

Test for the simple common things first (loom, socket, connections) before looking to the LCM or GM.
 
#133 ·
Another Trunk Cable Problem Fixed

Hi All,

my first post, and first of all a big thank you for helping me fix some long-standing problems. :)

For about 2 years now I have had at first intermittent, and then more or less permanent problems with the trunk latch. Initially the remote stopped working, or would only work occasionally, likewise the button inside the cabin had no effect. Always using the key in the lock on the trunk would open it fine. For quite a long time whenever I opened the trunk the latch would "cycle" often a few times in succession. When I first researched the problem, most responses focussed on the actuator, but this didn't seem right to me since I could hear it working, it just didn't respond to the remote or electric control.

For about a year now I just used the key to open it directly, which has been pain, especially when passengers want something from the trunk and you have to get out and open it for them.

Anyway, I had some spare time to decide to give it another go, I'd also had the FSU go (it is a '99, with 222k kms :dunno: ) PLUS the interior lights had stopped working and the rear doors seemed to have no power (Windows not working, central locking not working, speakers not working), so I was extra motivated to get fixing!

I checked the fuses, triple checked them, still nothing. Finally I found this thread, and for the sake of completeness decided to check the trunk cables. See first pic !! I'd struck gold !

See the rest of the pics for the details of the repair.

I started by cutting the remaining wires all at about the same place that the others were broken. I assumed (correctly so far) that I would simply rejoin like colors to like, and all the browns would be common. I couldn't see how to remove the entire harness from the car, although I assume it must be possible. I took some photos to help remember which went where.
Then I removed the wiring harness from the trunk lid.
Back to the workshop (it was cold outside and easier to work indoors! ) to tidy up the remains and splice in a couple of extra inches to each one. I had some spare speaker wire around that was about the same gauge, if not a little thicker.
For insulation I used a length of heat shrink that covered the full extent of the spliced in wire and the two new joints in each, but didn't shrink it until I was back at the car.
Back to the car for reattaching the lengthened wires, and a few minutes of soldering.
Slide the heat-shrink into place, and shrinked it in place using a cigarette lighter (more portable than a heat gun, and bit more controllable).
I then wrapped the bundle in narrow duct tape, which I find sticks better than PVC, and put a few squirts of teflon spray in the rubber trunking for good measure.

Reattached the rest of the harness, gave it a final check before putting everything back and...

NOTHING !!

This had taken me a few hours by now, and it was near freezing outside, so you can guess I was not happy!!

A couple of days later I decided to check it over again. I'd already reset the battery (left unused for a few minutes etc.) and this had had no effect, still no trunk, and no interior lights, locks etc.

After some more searching, I decided to check the General Module 3, just behind the glove compartment, as this seemed to control some of the systems I was having trouble with. I crouched down to see if I could take it out, and the largest connector going in to the module was unplugged!!! I think I had removed it when checking fuses etc for protection and better access.

I plugged back in the connector and: all interior lights working, central locking working and the TRUNK now opens from the remote !!! Repaired !

Thanks all once again for a great deal of help and no doubt a few hundred dollars saved from the dealer.

Cheers and happy new year,

Giles
 

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#135 ·
I had this issue and respliced like 5-6 of the wires in the harness. It took care of the problem for now. I gave the wires a good wrap with electrical tape to give them a bit more insulation. It is just a bad design as the opening and closing of the trunk lid over time causes the insulation on the wires to wear.
 
#136 ·
I had this issue and respliced like 5-6 of the wires in the harness. I gave the wires a good wrap with electrical tape to give them a bit more insulation.
We need pictures of the repairs please.

BTW, for the cross-linked record, this problem today turned out to be the trunk wiring loom:
- E39 (1997 - 2003) > Trunk problems

The other day I closed my trunk and then later when I tried to open it it would not open. It will not open by using the handle above the license plate, the remote button or the trunk release in the car. The only way I can open the trunk right now is by using the key and turning it CCW to the nine o'clock position in the key hole. Also, now my lights do not work in the trunk and I have the indicator light on my dash showing that the trunk is open.
Found four wires broke. Spliced them back together. Everything that didn't work before is working again.
 
#137 ·
Here are pictures of my truck repair. Picture 1: everything is spliced back together and taped. Picture 2: close up of picture 1. Picture 3: Trying to get everything back into the protective sleeve. Picture 4: Everything buttoned up and looking good, notice that I sliced the protective sleeve long ways to make it easier to get to the wires to make the repair. I also had to replace fuse #53 after everything was put back together. Sorry for not having any pictures of the repairs being made, but is very simple. Just remove insulation from end of broken wires and twist back together and tape with electrical tape.
 

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#138 ·
Bluebee,

Add another dark blue 2002 530i with the trunk wire loom problem to your list of blue bimmers with this problem.

Had a right side plate light out. Changed bulb and nothing. Referred to this thread, opened my loom and sure enough 2 wires broken. Grey with black stripe and red and black both split in half. Thank u for your past research on this! Will fix tomorrow.
 
#141 ·
Sammich.....just to be safe, take fuse 53 out and look at it close and even put a new fuse in just to make sure. I looked at my fuse 53 and thought that it was good also. It wasn't until I took the fuse out and looked at in better light that I could see that the fuse had burned through and that it needed replaced.
 
#140 ·
The issue here is that the insulation used on the wires is likely "German Environmental approved" It's got poor plasticizers in the insulation and it pre-maturely hardens and thus cracks when bent repeatedly. Once cracked, the copper wire now flexes within the crack and quickly breaks. Another solution to this if you have cracked insulation only, is to get 3M electrical tape, cut a long piece and wrap the wire carefully. The 3M tape hold up well.
 
#142 ·
This Blue thread is the second best bimmerfest discussion for my E39.
 
#143 ·
Great info!

On my 2000 M5 my trunk switch (the finger-one under the trunk lid) stopped working, but the kick panel switch and the remote still unlock it.
After reading this, I checked my wires and snorkel. I have at least one completely broken and a few pinched wires. I'll update with wire colors and function once I fix the break.

Just a heads up for another symptom that might indicate trunk wire failure.
 
#145 ·
Many thanks all! I fixed it tonight:

My grey/yellow stripe wire was broken. When connected, my trunk handle worked again! My fix was to solder and shrink wrap it.

A couple other wires had insulation cracking as well and I'm certain it's because of the material used as insulation not staying pliable. Since no copper was broken on those, I taped them up individually for structureal reinforcement.

Then I wrapped some tape around the whole bundle to hopefully increase the bend radius enough to prevent future problems while not just shifting the sharp bend to a more inconvenient part of the wires.
 
#146 ·
Many thanks all! I fixed it tonight:

My grey/yellow stripe wire was broken. When connected, my trunk handle worked again! My fix was to solder and shrink wrap it.

A couple other wires had insulation cracking as well and I'm certain it's because of the material used as insulation not staying pliable. Since no copper was broken on those, I taped them up individually for structureal reinforcement.

Then I wrapped some tape around the whole bundle to hopefully increase the bend radius enough to prevent future problems while not just shifting the sharp bend to a more inconvenient part of the wires.
This is the exact problem that I have, just the pushbutton on the trunk lid itself is out. I will check mine tonight.
 
#147 ·
For the cross-linked record, sometimes an inoperative trunk latch is not due to frayed wires in the trunk loom, as shown by this thread today:
> E39 (1997 - 2003) > How to remove the trunk lid switch?

I finally did get it out. Previously I was able to start pulling the switch out by using a small screwdriver inserted into the small notch of the switch and pulling down. I just didn't pull enough. It's kind of like a down and back motion to get it out.

I had actually already found two broken wires in the rubber conduit.. I repaired those and the switch still didn't work. The switch felt like it was broken (just didn't feel like it had any motion).

Once I had it out I could see the issue.

The rubber switch cover was pushed inside the housing (on the side closest to the inside of the trunk). The rubber was binding the switch and not allowing it to move. Once I got the rubber switch cover back into place the switch worked perfectly.
 
#148 · (Edited)
If it makes anyone feel better, my white 2003 540 has broken insulation on the harness. I inspected it yesterday on a whim just to prevent any issues. (I have not had any issues yet, 130,000 miles.)

I wrapped the two wires that were cracked. I wrapped another that looked brittle. Then wrapped the entire bundle.

My breakage occurred where the harness has to fold once the trunk lid is closed. When new, the harness complies, as it gets old, the wires start to fold, bend, twist and tear.

I work for a truck manufacturer. I have seen these issues many times. One idea I have is to get a spring and wrap it around the harness, inside the rubber covering. You could DIY one from a strand of regular wire. The idea is that the metal would keep it from folding. But that won't really help the twisting action.

Another idea is to somehow get it to fold into circle shaped loop, not an S shape. But again, that doesn't prevent it from twisting.

My second repair will probably involve some "liquid electrical tape" and mold it into s single 'block' that keeps the wires separate and bound.

The best fix would be to re-route the harness to somewhere inside the trunk so it doesn't have to fold at that joint.
 
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