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252K views 152 replies 57 participants last post by  00323ciE46 
#1 ·
I knew this day would come.

Earlier this week, the trunk refused to open when I hit the interior trunk release or the button on the key. I could only open it manually by turning the key in the keyhole. The trunk interior lights didn't come on when I opened the trunk, and the trunk-open light in the instrument cluster was continually lit. It occasionally flickered over hard bumps.

I'd done this repair once already - several years ago, on my 1997 328i. (See signature for details.) When the trunk lid wires on that car frayed and started to cause short-circuits, the central locking system fuse kept blowing. My E46 didn't do anything that exciting, thankfully.

After some exploration today, I found that the ground wire for the trunk lock actuator was completely severed after years of bending and kinking. See the attached photo. All of the other wires in the bundle (16 total) are still intact, but they're bound to start fraying too. Since there doesn't seem to be an affordably priced E46 replacement harness available at BMW dealers, I'm going to splice all new wires into the part of the harness that passes from the body to the trunk lid. I already have a new rubber cover and splice connectors; I just need to purchase the wire. The wires in the trunk lid are all 18-gauge and smaller, and the wire I have on hand is just too big for 16 of them to pass through the rubber cover. For now, I've spliced a short length of new wire to replace the broken wire, and the trunk lock and trunk lights are working.

I will update this thread with observations and tips after I complete my repair. If you're having trouble with your license plate lights, reverse lights, or the trunk lock actuator, you might want to check for frayed wires.
 

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#61 ·
Thank you for the excellent write-up on this. I wouldn't have thought to trace out the whole harness, but if you're going to do a job right...

I went to the McMasters-Carr website and was overwhelmed at the variety of wire available there. You wouldn't happen to have the item numbers and length of wire you purchased available? They say imitation is the finest form of flattery.
 
#62 ·
I went to the McMasters-Carr website and was overwhelmed at the variety of wire available there. You wouldn't happen to have the item numbers and length of wire you purchased available?
Thanks for the compliments. You can narrow your McMaster search to crosslinked-PVC-insulated (XLPVC) wire by selecting "UL 1429" under the "Type" heading in the left sidebar. Then you can select the gauges and colors you want. Choose as many colors as makes sense to you when you rebuild your car's wire harness.

Good luck!
 
#66 ·
Thanks for this thread as it's given me a good starting place for my Problem. I have a 318Ti and the boot (trunk) lid won't stay shut. Every time we close it, you hear the automatic release mechanism activate and unlock it again. Only once the car is fully locked will the boot stay properly shut. We are having to drive the car at the moment with the warning light on on the dashboard and witht eh boot lid only shut on it's safety catch.

It certainly seems to be a short circuit as the problem has got increasingly worse over the last couple of weeks.

R
 
#68 ·
Thank you for this informative posting because I too am now dealing with this problem. I've decided to avoid the frustration and just replace the entire loom at $500. But what I want to know is whether or not the wire loom comes with a new rubber hood or if that is a separate purchase? I can not find a separate rubber hood on RealOEM and the parts stores that sell this piece (61126919968) do not know if the rubber hood is with it or not. Thanks for the help!
 
#69 ·
Thank you for this informative posting because I too am now dealing with this problem. I've decided to avoid the frustration and just replace the entire loom at $500. But what I want to know is whether or not the wire loom comes with a new rubber hood or if that is a separate purchase? I can not find a separate rubber hood on RealOEM and the parts stores that sell this piece (61126919968) do not know if the rubber hood is with it or not. Thanks for the help!
Have you confirmed that the part number is for a complete replacement trunk lid harness? My local dealer parts guy wasn't able to do so, and I didn't want to gamble $500 on a special-ordered electrical part that I couldn't return.
 
#70 ·
I talked to three sellers of the part with that number given to them. They tell me that is the correct harness for my 2001 (March) 330i. But nobody can tell me if the hood is part of it. The best they can do is tell me that they do not find the hood listed separately in the diagrams or catalogues.
 
#71 ·
You know, I kept wondering why this thread continued to be a sticky for so long, until I was a victim...

Anyway, I need to go in and splice a couple of wires (driver trunk release button not working and getting an intermitent dash warning light that I've got a rear brake light bulb out). Questions:

1 - When I get to the wires, do I need a gauge measurement tool to determine gauge of the specific wires I need to splice?
2 - I need to keep the rubber boot in tact I assume since I'm not replacing the entire loom, i.e. it is one solid rubber tube?
3 - If I'm just splicing, should I go with the recommended XLPVC replacement wire or should I select something more in line with the OEM wiring I am splicing within? Or will either work just fine?
 
#72 ·
1 - When I get to the wires, do I need a gauge measurement tool to determine gauge of the specific wires I need to splice?
If you have a caliper, you can use it to measure the diameter of the bare wire and then compare the measurement to the values in a wire gauge table.

2 - I need to keep the rubber boot in tact I assume since I'm not replacing the entire loom, i.e. it is one solid rubber tube?
It's one continuous corrugated tube. To replace a cut or damaged boot, you would have to cut the wire harness inside the car, thread it through the new one, and re-splice all of the wires.

3 - If I'm just splicing, should I go with the recommended XLPVC replacement wire or should I select something more in line with the OEM wiring I am splicing within? Or will either work just fine?
I haven't taken a close look at my two-year-old XLPVC wire harness, so for now, I'll just say that XLPVC or a quality (read: not the cheap auto parts store stuff) PVC- or XLPE-insulated wire should make for a good repair that, depending on proper splicing technique, climate, and usage, should last for a few years.

Be aware of the wire vendor's minimum quantities if you order by mail.
 
#76 ·
trunck wirng

I read through this once and an while and fast bob always respond (thanks) sorry to digress

The trunk lid wiring worries me. I am wondering how much the trunk is used on these cars that it breaks, Can someone comment? I want to be proactive as I have already had trunk seal issue that the SECOND dealer found and fixed. First dealer told me to park on level and it wont leak, unbelievable for a dealer... Never going back there. (Orange county BMW NY)
 
#77 ·
I have determined I have a broken wire, but not sure where the break is, but per this thread the most likely area is in the rubber booth that covers the harness between the trunk lid and the trunk area.

My question is: Assuming it is a broken wire in the area of the harness covered by the rubber boot, what is the best way to investigate it WITHOUT cutting into the boot? Is there a way?

I just want to splice the fix. I don't want to redo the harness because I just don't have the time, nor the inclination for something like this.

I cannot see any way to "slide" the booth in either direction enough to look in the area under the middle of the boot without either cutting something or maybe disconnecting something.

If I disconnect all the connectors in the trunk lid, is there enough "play" to pull a length of the wiring harness out of the trunk lid so that I can slide the rubber boot along the harness so that I can uncover the length of harness that the boot originally covered?

(all the reuse of the words "trunk", "boot" and "harness" makes me think of the phrase "how much wood could a woodchuck chuck if a woodchuck could chuck wood")

Thanks for any ideas or recommendations. I just want the fastest fix possible without taking it to the dealer and paying through the nose.
 
#78 · (Edited)
If I disconnect all the connectors in the trunk lid, is there enough "play" to pull a length of the wiring harness out of the trunk lid so that I can slide the rubber boot along the harness so that I can uncover the length of harness that the boot originally covered?
I think you should be able to get some more slack in the harness by unplugging it from all of the accessories in the trunk. Make sure to tie a string to the end of the harness so that you can fish it back into the trunk when you are finished with your repairs.

Your existing boot will surely be less flexible than a new boot. Pull on it carefully, and if it should crack or tear, be prepared to wrap it tightly in electrical tape, then replace it when you have enough time to do so.

Also, when you locate the broken wire, consider splicing in a new length of wire at the point where the harness flexes, and locate the splices a few inches away where they'll be subjected to less flexing. A splice made right at the bending point won't last long.
 
#79 ·
E46 convertible license plate lights & trunk release solution

For E46 3 series convertible license plate light and trunk release issues

Hi,
I am newly registered to this forum and wanted to "give back" by contributing some helpful information for those with 3 series license plate light and/or trunk release issues.

I will start by letting everyone know that the dash warning/indicator lights WILL come on when your license plate lights are not working. (I have seen several debates on these forums about it) I can assure you, BOTH taillight/brakelight indicator lights will show up if the license plate lights are out. There are only 3 wires going to the license plate lights AND the trunk release button on 3 series convertibles when you access it in the very back (not sure about the coupe but probably the same). The trunk carpet on the trunk LID must be removed and all this can be easily accessed. If any combination of these wires are compromised, corroded, broken, etc, SOMETHING will not work, whether its your L license plate light, R license plate light, or trunk release. You can get in there and inspect the components and wires for corrosion or breakage. There are easily accessible screws and the BMW emblem on the convertible trunk must be pried off as there is one screw under there as well. If you have lost either of the 2 lenses that cover the license plate lights, corrosion is likely. In my case it was bad as the lens may have been off for 2 years or more! Clean the corrosion off of the license light housing and connectors and reattach any wires that may have been compromised. If the problem is not solved here, read on.

For me, the problem not only as previously explained but ALSO in the "elephant trunk," which is the little rubber hose on the inner right side of the trunk near the hinges and hydraulics when you open the trunk. VERY EASILY ACCESSIBLE with no tools as you can see it as soon as you open the trunk. This rubber housing contains 13 wires and over time these will break from opening and closing your trunk. The integrity of the wires become compromised right in the middle. I just cut the elephant hose CAREFULLY off without cutting any wires so I could fix all the wires without the rubber housing impeding. After I fixed each wire, I used electrical tape to cover each individual wire. Even if they weren't broken I covered with electrical tape to give them additional support from the ferocious trunk lid. Brace yourself...11 of my 13 wires were either badly frayed or completely severed. I am surprised ANY electrical components on the rear section of my car worked! After reattaching/repairing all of these wires in the "elephant trunk" all of my dash lights and indicator lights went out and my license plate lights work again!

NOTE: Again, of those 13 wires, only 3 of these go to your trunk release and license lights. So if the problem is not at the elephant trunk, it will likely be directly at the trunk release component and one of those 3 wires will have issues in that area. I also discovered that it IS POSSIBLE for the trunk release to be working and not the license lights, or vice versa, depending on the combination of which 3 wires are out.

I hope this helps someone in the Bimmerfest community and I am thankful for all you guys have helped me with over the years on my car! Since my car is racking up the miles, I will continue to contribute as I fix the issues.
 
#83 · (Edited)
I'm sorry I missed the earlier plastics discussion.

I used Tefzel (ETFE) insulated wire which is commonly used in commerical aircraft with a minimum, 40 year design life. Tefzel insulated wire is thinner which increases the bending radius and decreases the bundle diameter. The only drawback I have found with the stuff is that it is harder to strip. I use a self-adjusting wire stripper.
 
#84 ·
@GP Burdell Great post with great information! I just completed the patch today and while my back is going to be sore tomorrow at least I will be able to open my trunk with my FOB!

A couple things I noticed that were a little different:
- I only had 14 wires in the harness itself (I think this is because I dont have an interior trunk release button)
- I ordered 18,20 and 22 gauge wire and while I used all three I probably could have gotten away with only the 18 and 22 gauge

Also for other to reference, it also took me about 8 hours to complete and I chose to solder the connections vs the crimping, so plan a full day when you do this.

Past that I everything else was the same, so thanks again!
 
#85 ·
@GP Burdell Great post with great information! I just completed the patch today and while my back is going to be sore tomorrow at least I will be able to open my trunk with my FOB!

A couple things I noticed that were a little different:
- I only had 14 wires in the harness itself (I think this is because I dont have an interior trunk release button)
- I ordered 18,20 and 22 gauge wire and while I used all three I probably could have gotten away with only the 18 and 22 gauge

Also for other to reference, it also took me about 8 hours to complete and I chose to solder the connections vs the crimping, so plan a full day when you do this.

Past that I everything else was the same, so thanks again!
Glad to help. Thanks for sharing observations from your repair! :thumbup:
 
#90 ·
[I own an E36 and almost feel I should disqualify myself from posting...]
If you're responsible for the E36 rear fog lights article on Unofficial BMW, then you're entirely qualified to post. :)

Also, a status report. After three years in service, my rebuilt trunk wire harness is still going strong, with no problems.
 
#89 · (Edited)
Guys, the e46 wiki has some info that will help. Electrical section:

http://www.bimmerfest.com/forums/showthread.php?p=8014505#post8014505

Unfortunately I think the recall affected 2002-2005, but there is a link to the DIY repair in there. If your plug is melted to the point that the wires aren't isolated, and are therefore arcing or shorting out, you may just have to get a new plug. But you should add another ground wire as well, just to be safe, as indicated in the DIY. Usually there is a tiny bit of melting, but the plug can still be used.
 
#91 ·
New guy

Hey 'festers

I found my way to this thread because my Viper alarm has started telling me that the trunk is open, when I arm the alarm. And of course, it's not. I'm guessing it's the wiring in the trunk. So I read this thread, and tried to get my hands on XLPVC or ETFE wire, but for unknown reasons, that isn't easy where I live.

So in the Danish BMW-club forum, a guy posted a thread, telling about this:

http://www.ebay.de/itm/Kabelbaum-Re...its=Make:BMW|Platform:E46&hash=item3cdb508f9a

A repair kit for the trunk, complete with boot and crimp connectors. It's a little expensive, but considering the amount of time saved, it's pretty attractive. These guys use silicone for isolation...

Amazing how this thread has stayed alive for more than three years :)
 
#92 · (Edited)
So in the Danish BMW-club forum, a guy posted a thread, telling about this:

http://www.ebay.de/itm/Kabelbaum-Re...its=Make:BMW|Platform:E46&hash=item3cdb508f9a

A repair kit for the trunk, complete with boot and crimp connectors. It's a little expensive, but considering the amount of time saved, it's pretty attractive. These guys use silicone for isolation...
That's very interesting. Thank you for sharing the link.

If I were buying this product, I would want to make sure the number and size of the wires in this aftermarket replacement matched the wires in my car's wire harness. Also, because this replacement requires all of the splices to be made at the same point, fishing that big bundle of 16 butt connectors through the hole in the trunk lid might not be easy.
 
#94 ·
All done, soldered and heat shrinked, nice and tidy. Took me about 2 hours. Would have taken maybe 15 minutes had I used the crimp connectors.

I had one ground wire where the isolation had broken - the conductors were still intact. So obviously this hasn't fixed my problem... but now the wires wont ever be a problem. The wires in the repair kit have a high number of thin conductors, making them more durable to bending. The isolation material is very soft, slick and flexible (silicone), so rubbing and bending at any temperature wont do any damage in my lifetime.

Now I just have to find a new lock mechanism for the trunk, since that's were the trunk sensor is located :)
 
#95 ·
Hello i notice you know a lot about bmw's so i wanted to ask you a question. My head lights flicker off and on now. every few seconds my lights will just flicker for no reason at all. Does anyone know whats going on and how i can fix it? also my car vibrates pretty hard when i am not moving at all does anyone know whats going on. Please let me know.
 
#96 ·
Do you have xenon?
If not, it's probably just a defective relay. Relays are in the glove compartment, together with the fuses.
If yes, then you most likely need new ballasts (xenon ignition power boxes).

The vibration could be a lot of things. Does it get worse when you rev up the engine?
If not, check your spark plugs and ignition coils.

If yes, check the vibration damper on the crank shaft - there's a center rubber mount that can go bad. Your flywheel could also be a source of vibration.
 
#98 ·
No i just have stock lights. And I was told it might be my motor mounts or some thing like that.
Hm.. I just found out, the head lights have no relay. Only the fog lights do. The head lights are fed from the light module or the arm on the steering wheel. So it must be one of those, if it's not a loose bulb plug.

Engine mounts can cause vibration too. Do you have one of the bigger engines? The bigger the engine, the more likely it is that you've teared the engine mounts.
- but I still think, that if your engine runs smoothly, then even an engine mount shouldn't cause a lot vibration. The engine would, however, move around a lot when revving it. With new engine mounts, I think the engine should move less than 1 cm (3/8 inch) when revving.
 
#99 · (Edited)
Just to let you know, an E46 team member asked over in our canonical thread on the trunk loom fraying:
> E39 (1997 - 2003) > E39 Electrical Problems Traced to Trunk Lid Harness Wire Chafing (DIY Diagnostic)

We pointed them to your canonical thread, which is even a sticky, so, it's easy for them to find:
> E46 (1999 - 2006) PSA: Check Your Trunk Wire Harness

My e46 (automatic) has no reverse lights coming on. I can't seem to find them listed on the wiring charts anywhere in this thread. Am I missing something? I inspected the wiring at the snorkel and even tried pulling the wires apart looking for a break and couldn't find any. My fuse #27, I believe, was blown and I replaced it, but still no reverse lights. Thanks for any help you might provide.
Since the reverse lights are not in the trunk lid, I don't think any issues related to reverse lights have been proven yet. It's not a bad idea for you to have checked your trunk wiring, but it might not be the problem.
Okey, thanks. I'm not able to check the wiring because i'm offshore right now. Was takling to my girlfriend, and the told me about this trunk lid problem one day, and the day after she wasnt able to lock the car with the keyfob.

The wiring was my first guess, but wanted to ask because of the locking problems.
This is an E39 forum. You'll have more luck in one dedicated to E46s.
The E46 guys had created their own thread, which they even made a sticky, so, I'd suggest the OP try that.
- PSA: Check Your Trunk Wire Harness
EDIT:
PS: What does "PSA" mean anyway?
 
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