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Thread: Fixing the trunk lid wiring harness

  1. #1
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    Fixing the trunk lid wiring harness

    When I first got broken wires in the wiring loom I just soldered the wires back together but that fix didn't last. Under a year and I got more broken wires. So I decided to pull the wiring harness and replace the section that get bent each time you open or close trunk. Since Imageshack is having some issues I made it into a PDF. Due to forum restrictions I had to compress it quite a bit so quality isin't the best possible. Anybody got any comments?


    Update: I uploaded a new version of it on filefactory. The PDF is now over 4 MB, so the quality should be better. Link

    Update: New link
    Last edited by Spirit Force; 03-23-2015 at 04:22 PM. Reason: New link to the guide

  2. #2
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    Excellent write up. I've noticed this too after I soldered the trunk release/open and less than a month later it broke again. So the wires are just too short?

    "Life is a numbers game. Increase the numbers, win the game"

  3. #3
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    The wires aren't too short, they just get bent too much. I think the original wiring is PVC insulated, which doesn't take too well being bent that much regularly. Just take a look at the rubber loom when you close the trunk. Wires get twisted into U shape.

  4. #4
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    May have to splice in some very finely-stranded wires.


    Ed in San Jose '97 540i 6 speed aspensilber over aubergine leather. Build date 3/97. Golden Gate Chapter BMW CCA Nr 62319.

  5. #5
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    Thank for the contribution. I'll tow this to the DIY section after comments.
    Fyi, first link in PDF is broken (at least for me).

  6. #6
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    Excellent write up. What were the symptoms that made you check the harness? It seems that this only affects blue cars lol.

  7. #7
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    Quote Originally Posted by jamesdc4 View Post
    Thank for the contribution. I'll tow this to the DIY section after comments.
    Fyi, first link in PDF is broken (at least for me).
    Thanks for the heads up. I first began writing it on the forum and only discoved the imageshack wasn't working when I was almost ready. I couldn't upload pictures to imageshack, so I just copy pasted it to MS Word. It seem that I forgot to fix the first link after that. Oh well I'll be doing some minor fixing on it anyways. I'll upload a better quality PDF to imageshack and put a link for it in the first post. How long can I edit the first post? Can I edit it after it's been towed to DIY section?

    Quote Originally Posted by GreenTiger View Post
    Excellent write up. What were the symptoms that made you check the harness? It seems that this only affects blue cars lol.
    Thanks. The issues were: trunk wouldn't open via remote, inside switch, or the trunk switch. Only turning the key 90 degrees would open it. What a pain in the ass to use the key each time! Mine isin't blue it's Cosmosschwarz

    - - - Updated - - -

    Uploaded new version on filefactory. It's a better quality (over 4 MB). Added some more info and few new pictures.

  8. #8
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    Hello.
    The link is not working anymore. Does anyone have a copy of this DIY?
    BMW Addicted

  9. #9
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    1989 325i, 2001 530i 5MT
    I'd love to see this too. Both trunk lights out. Verified broken wiring harness at the pass side trunk lid hinge. For the moment the remote release still works, both at the button at the driver's door jam and via the remote key fob.

    I'll keep an eye out for a fixed link .

    - - - Updated - - -

    Well this is interesting. Hopefully we're talking about Part #4 in the diagram, not Part #3...
    For that push off the cliff, this one GOES211...

  10. #10
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    New to the forum, just bought a 2003 530i and seem to have all the typical issues for this model/year. Found the trunk wiring harness issue while replacing tag lights. Has anyone found a good fix for this? Right now all I know to do is cut wires one at a time, butt solder together, and cover with heat shrink. Not much extra length in wire to play with.

  11. #11
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    I was able to fix the trunk wiring harness this weekend. I had to cut each wire and solder back with a inline joint. I have too say probably the worst soldering job I have done in my life. It is very hard to keep the wires together in a vertical position in the corner of the trunk with soldering iron in one hand and solder in other. Not to mention it felt like 120 degrees outside with humidity 1000%.....LOL The design for that harness is the worst I have seen. I recommend carefully slicing the rubber harness length wise the entire length, pulling all the wires out and doing the repair. Make sure to use heat shrink on each wire. When done you will be able to slip the wires back into the harness and use 3M Scotch 33 black tape to wrap around entire length of harness.

  12. #12
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    Did anyone save this PDF and can upload it again?

  13. #13
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    I uploaded it again, but it will dissappear after 100 days, if noone downloads it. Anyone got any suggestions on a good upload site that has no expiration?

  14. #14
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    Quote Originally Posted by Spirit Force View Post
    I uploaded it again, but it will dissappear after 100 days, if noone downloads it. Anyone got any suggestions on a good upload site that has no expiration?
    Upload to Photobucket, then just put the link here, but make sure your privacy settings are not requiring a password, lol

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