Attention: ALL E36 owners beware - WIRING PROBLEM

[ed323i]

Checked it out this morning.. 4 wires cut.. That explains the not working trunk lock actuator.. I haven't figured out yet what the other 3 wires do, or what functionality I was missing..
I'll be doing some soldering tomorrow. Great that all lock actuators now finally work (I fixed it very temporarily with a screw terminal).

Tip: You never have to cut the wire harness/isolation.. From either side you can wrinkle/compact the isolation to about 40% of its original size, with some effort.. So if you do that from both sides (one side at a time) you can uncover and inspect (and if needed repair) all wires.. You want it to eventually be water proof again as the wires are located exactly where water flows when it's raining (or if you're washing your car)..

I found this article quite interesting:
http://www.lsxmag.com/tech-stories/t...ing-a-racecar/

[MParallel]

I might check it out of curiosity.

But both my E36’s, now 20 and 22 year old,
I never had blown fuses, weird acting trunk lock actuator, failing license plates and such.

Years ago when I first read about this, I removed the last clip so it doesn’t kink as sharply as with it.

But since so many have broken wires, it does make me wonder. The 22 year old is my daily though and the trunk gets opened and closed multiple times a day.

If anything, these wires should be broken...

[E36328Coupe]

Tip: You never have to cut the wire harness/isolation.. From either side you can wrinkle/compact the isolation to about 40% of its original size, with some effort.. So if you do that from both sides (one side at a time) you can uncover and inspect (and if needed repair) all wires.. You want it to eventually be water proof again as the wires are located exactly where water flows when it's raining (or if you're washing your car)..

Easier tip

Most of the issue appears to be work hardening of the copper not chaffing of the sleeve. Using different sleeve materials won't alter that, you would need a different conductor.
What I did was slide the guide along so the curve was not as sharp once fixed so would take longer to go next time.
I replaced a few inches either side as no point just soldering the ends back together to break sooner.
I pushed one grommet through into the boot and pulled the other out of the boot lid and slid the whole thing down the wires.

You may have to pull the grey tubes out the grommets

[JDStrickland]

TIP
Remove the liner from the trunk lid, and take the grommet out of the trunk lid and push the rubber sleeve down and pull the wires up. You should be able to get the wires to connect. It is advised that you do not cut the rubber sleeve open to expose the wires that need to be repaired. With the trunk liner removed, you can see more of the wires, and you can unplug a couple of them to create slack to make repairs, then connect them back where they belong.

[JasonMHorn]

I didn’t read all 30+ pages, but what the OP is about happened to me. I recently purchased a 1994 325i and while out on its (mine) maiden voyage I noticed that none of the rear lights worked and neither did my dash lights. I initially thought that the lights were the bulbs. I went for the rear lights first. After trying to replace the bulb I realized that the bulb wasn’t the issue so I went to the fuse box. I found the 10amp fuse popped and replaced it. Everything was perfect until I went to close the trunk. As soon as I closed the trunk the fuse popped again. After several fuses I realized that it blew when the trunk lid was about half way down. I did a quick Google search and found out about the wire issue. I’m not super happy about the way that I went about it but it was late and I was tired, I took a razor blade and made a smile incision in the wireloom. It was enough to see frayed wiring. So immediately I knew what the issue was. I made the incision big enough to wrap electrical tape around 8 of the 9 (if I recall correctly) wires. Once that was done I put a new fuse in and carefully closed the trunk lid halfway and everything was good. So I closed the wireloom tight and wrapped electrical tape around that too.

I plan on going back and using shrink wrap instead of the electrical tape when I get a chance.

I also pulled the wireloom out of the clips including the trunk lid strut clip which I had to remove the bottom clip from the strut to do so. This allowed for easier access to the wires.

Apparently this is a very common issue. Good luck with yours. IMO I wouldn’t panic about it unless the fuse blows. And this is also why it’s very important to use the right fuse.

[E36328Coupe]

^ Cutting the original sleeve - bad idea
Shrink wrapping so wires are held tighter and chaff / kink - bad idea

[MParallel]

I checked mine. You can easily pull the grommet out of the trunk(boot) and push it down the loom, pushing back the sleeve.

Well, maybe it’s the exception that prooves the rule, but all my wiring is 100% ok. I took pics if you want to see.

All it has was a litte cut at the outer black sleeve, which now that I saw it, but some black electrical tape over back in 2006.

[johnf]

...Shrink wrapping so wires are held tighter and chaff / kink - bad idea

I agree. You want to make the conductor bending radius as large as possible – at least 15 times the wire diameter if you can– and that means even where it is sharpest in the flex zone. You don't want a radius that is the 5 times or less, as I have measured off the end of the original, stiff, trunk lid feed-through tube.

You are just asking for trouble making splices in or near the flex zone, whether you insulate them with heat shrink or electrical tape. Consider where BMW has you splice in their repair harness.

[JasonMHorn]

^ Cutting the original sleeve - bad idea
Shrink wrapping so wires are held tighter and chaff / kink - bad idea

How would you recommend protecting the exposed wires?

[johnf]

Run a new set of wires through the trunk-to-trunk-lid cable and splice them into the old wiring: inside the trunk and inside the trunk lid – where it will not get bent. Insulate with electrical tape, heat shrink, goop or whatever, to avoid strain, corrosion and electrical contact.

If you plan to keep the car awhile, use wire that remains flexible at low temperatures. The stock PVC wiring doesn't and has lost plasticizer over the years. PVC wire without that is as flexible as PVC drain pipe, although in this case, it will probably crack and crumble.

[M3AN]

I checked mine years ago and there was some damage. I 'fixed' this with electrical tape which lasted a long time until I got my repair harness. I recommended eventually fixing it permanently but tape works just fine for ages.

If you do it with the new harness remember to tie dental floss (or similar) to the tails and plugs of the original harness before you pull it out so you can feed the new ones in easily. Add a connector in the trunk if you're going to swap over your trunk/spoiler in the future. Also put the main retainer clips back in the optimal position as mentioned earlier in the thread.

TrunkLoom.jpg

LoomPlugs.jpg

[MParallel]

^^
Don't put the original retainer clips back. At least not the one closest to the bending point. This clip is the reason the loom kinks so hard.

[E36328Coupe]

How would you recommend protecting the exposed wires?

With the un-cut original cover

[MojoE36]

Just chiming in with my experience. I had several of the symptoms from this thread. Burned up a check control module and traced it back to the trunk wiring. Had broken and fused wires in the exact location you guys have mentioned. I can't believe I never saw this thread before. Cut, re-soldered them, and sealed them in heat shrink. That clip is definitely causing a lot of strain and the wires seem to have lost all their flexibility along with them not being twisted in the loom, so a lot of rubbing was going on. definitely a major problem that every e36 owner should go ahead and fix even if the symptoms don't seem to be happening. This could easily burn down a car, house, or any car parked next to yours. This is an easy fix. Don't neglect it.

Edit: If you haven't already figured this out. Don't cut the sheath like some people have done. Spray a towel with some silicone lubricant and rub the loom. Slide the original cover down and do the repair. cutting the wire will only result in a junky repair and exposes the wire to more moisture unnecessarily.
942615690286593587.jpg6608125661496300080.jpg123877675840795632.jpg

[BMW328ilover]

Hello everybody. I just recently bought a red 1997 BMW 328i and she has no major issues except one issue that has to do with the lighting on the instrument cluster. I noticed that when I was test driving her there was a message from the OBC that the tail lights needed work,and I wonder if that has anything to do with my issue because I've read on this site that people who had a similar issue reported their tail lights not working. I've replaced fuse #37 twice as I have read online and on the back of the fuse box lid that it operates the instrument cluster. When I replace the fuse, it either blows immediately or it works until I start the engine. When I started the engine at first I considered it could be an issue with the alternator. But I think that is unlikely. I've also read on this site that it might have something to do with the rear wiring loom. I was wondering what I should do myself before I take her too a mechanic or if that is necessary and I could fix the issue myself. If it is not necessary to see a mechanic, what could I do to repair this issue?

[M3AN]

Hello everybody. I just recently bought a red 1997 BMW 328i and she has no major issues except one issue that has to do with the lighting on the instrument cluster. I noticed that when I was test driving her there was a message from the OBC that the tail lights needed work,and I wonder if that has anything to do with my issue because I've read on this site that people who had a similar issue reported their tail lights not working. I've replaced fuse #37 twice as I have read online and on the back of the fuse box lid that it operates the instrument cluster. When I replace the fuse, it either blows immediately or it works until I start the engine. When I started the engine at first I considered it could be an issue with the alternator. But I think that is unlikely. I've also read on this site that it might have something to do with the rear wiring loom. I was wondering what I should do myself before I take her too a mechanic or if that is necessary and I could fix the issue myself. If it is not necessary to see a mechanic, what could I do to repair this issue?

Check it yourself first, it's easy and all the info is available in this thread.

You can get a repair harness from BWM if you want to replace all the wires or you can fix the existing ones. If you're okay with wires and electrics you can do it yourself, if you're not confident you can get a quote from an auto-electrician. It should only take 2-3 hours if you provided the repair harness.

[gc325is]

I will repeat, I think there is BMW design error as most aircraft, military even auto racing cable manufacturing says you twists the wires set to allow flexibility.
So if you patch some wires in add a twist.


"Concentric twisting refers to the way in which the different layers of wire in the harness are laid up. When you have a lot of wires in a loom, it can be challenging to run them all in a neat fashion and keep flexibility in the loom once it's shrunk with heat shrink. With concentric twisting, there are different layers and direction of the twist of the wires alternates with each layer. That keeps the loom nice and flexible, keeps everything neat and tidy and makes sure that none of the wires in the harness have more stress than others. In the images above, you can see how flexible the loom is. That's important when you are routing it in the chassis around bends and tight radiuses. The proper technique for concentric twisting is a complicated process, so instead of having to learn it we offer it already done for you!"

This BMW straight wire layout for a section that must bend is incorrect. It is OK for fixed wires looms not flexible one like at the trunk !
A simple 1 turn every 3 inches may be enough for trunk use in the bending area!



I see samples of BMW wires made fast and cheaper because less wires length is needed.



Wrong, but has some small twist if you are luck to get one installed in your car





Wrong, no twist




Wrong except for permanent flat use.









Correct design process.... That's important when you are routing it in the chassis around bends and tight radiuses. A lower 1 turn every 3 inches may be enough for BMW trunk use



This is a Sample harness comes with one half of the harness, the chassis side and the engine side. The chassis side is 48" long and has the 4 bolt flanged connector end of it. The engine side is 72" long and has the twist collar connector on it. These are suited to run up to an 8 cylinder engne with 8 injectors and 8 coils. All of the terminals on the connector are populated so you have a full connector to start with, preventing the need to buy the costly tooling to crimp the MilSpec terminals.
This was from milspecwiring.com

[johnf]

Even a twisted harness is going to come to grief because of the original, tight bending radius – and the stiff, upper feed-through tube that kinks the wires.

One of my neighbors, a former ship electrician, happened to walk by while I was surveying the harness and pondering what to do about it. He glanced at it, pointed below the tube and remarked it was going to break there.

[gc325is]

Maybe it the wires should be described as "not a twist" but more it act more like a spring expanding and collapsing instead of how everyone has the bending action in one area. It's Hard to explain but this is a photo of my trunk wire set from 2014 of this post. The wires seem to be pre curved and just be lifted up and down when the truck is opened.

The stress point is spread out and not centered in one area and the bend movement in total is less





trunk wire.jpg

[Mike WW]

It's unquestionably a bad design. One that allowed it to twist and not fold would have been much better. However even within the design it's poorly executed, the wire strands need to be smaller and the insulation more flexible. The replacement harness I got almost 10 years ago was much better in this respect. Probably still not what I would like, but much better.

Example, if you have a say 2MM wire with 17 strands in it, it's going to break much sooner than a 2MM wire with 100 strands in it. Plus while the original insulation was probably tough, it wasn't flexible enough itself, I had wires with broken insulation were the wire wasn't even broken yet.

The replacement harness, at least the one I bought was much higher quality and has not been an issue in over 100K now, whereas the original had already been (poorly) repaired at less than 100K.

[johnf]

... Plus while the original insulation was probably tough, it wasn't flexible enough itself, I had wires with broken insulation were the wire wasn't even broken yet....

Could that have been aged PVC that had lost its plasticizer?

If you still have the old wires, I would be happy to stick them under a microscope and post some images.

[Mike WW]

Could that have been aged PVC that had lost its plasticizer?

If you still have the old wires, I would be happy to stick them under a microscope and post some images.

Nope, long gone, I hang onto stuff too long but not that long.

It could be, but I suspect it was just the way it was manufactured. But the wire was much different too, the individual strands were much thicker on the original so less flexible.

[themusgrat]

I've had some intermittent problems, finally checked this last night. I don't think any of the wires are actually broken yet, but some of the sheaths are wearing, and some exposed wiring, probably shorting other wires.

Glad I read this first, and didn't cut the protective rubber. Grommets are pretty easy to get out. I got them out and put them back with my fingers, though as someone said, flat head screwdriver would make it even easier.

I'll post pics of mine if I think of it.

[john1in2]

Yes, the same problem happened to me about 10 years ago. Trunk loom wires all were rubbing together.
I was losing brake and license plate lights, and the trunk lock lost sync with the door locks.
So I can confirm you are correct.

[themusgrat]

I found additional damage by the left tail light. The wires were rubbing up against one of the plastic light bulb holders, one almost broken, another 3 with exposed copper.

My real problem is that when it rains, my windshield wipers stop working. I'm not sure why that is, but it could be that humidity or water is getting to exposed wires, and shorting them. I guess I'll have to find out if this fixed it next time it rains..