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Thread: 85' 325e stereo/headunit replacement

  1. #1
    Join Date
    Oct 2018
    Location
    New Jersey
    Posts
    10
    My Cars
    1985 325e

    85' 325e stereo/headunit replacement

    Completely confused by current wiring setup.

    I wanted to change my stereo / headunit in my 325e to a Kenwood KMM-BT522HD (Im open to changing what to use) and I'm truly bewildered by the current wiring.

    I removed the headset to see what I'd be working with and I haven't seen any other threads with this set of wires.

    (Gonna post pictures. Cant figure out how on mobile)
    Last edited by 85moonboy; 10-29-2018 at 11:26 AM.

  2. #2
    Join Date
    Jul 2011
    Location
    Arlington, VA
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    My Cars
    2018 BMW M240i
    The 1985 325e has a weird audio cabling system. I know, I owned this same car for 15 years and 3 different head units. The factory head unit has only 2 speaker level outputs!!!! Those 2 signals then got through the module in the dash that has a horizontal wheel sticking out of it. It’s some sort of an audio fader. See item #3 in the link, below. That module has the wires that go to the speakers.

    http://www.realoem.com/bmw/enUS/show...diagId=65_0034

  3. #3
    Join Date
    Oct 2018
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    New Jersey
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    My Cars
    1985 325e
    So basically all the parts I need to use in a new speaker are already in this, but they are just tucked away?

  4. #4
    Join Date
    Aug 2005
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    Crystal Lake, Illinois
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    86 325e Baur, 03 330xi
    Dump all that 1985 trash and rewire the car.

  5. #5
    Join Date
    Oct 2018
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    New Jersey
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    1985 325e
    Oh crap, I just realized I titled this thread a "speaker" replacement and not a stereo replacement.

    Man I've been all over the place on this site so far.

    Edit: to add onto my problems, I went to edit my first post and it then deleted what I had. So those messages are gone.

    Basically I want to replace my current stereo setup (in a 1985 BMW 325e coupe) , but I cannot find a post/thread that has my current wiring setup. I was planning on switching it out for a Kenwood KMM-BT522HD but I am not sure if it will fit. I'm open to changing stereo choice as well.

    Here are the links to the wiring I'm working with
    https://www.flickr.com/photos/165623...5/in/datetaken
    Last edited by 85moonboy; 10-29-2018 at 11:39 AM.

  6. #6
    Join Date
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    2018 BMW M240i
    You need to find the wiring diagrams for the car’s audio system. The fader in the dash needs to come out. BMW sells a piece that covers the hole in the dash. Then wire up the new head unit to wires they go to the speakers. Here you go: http://www.wedophones.com/BMWManualsLead.htm

  7. #7
    Join Date
    Jul 2011
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    Arlington, VA
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    2018 BMW M240i
    BTW, BMW sells a little black plastic piece that covers the hole in the dash where the fader unit used to sit. It was the cheapest part I ever bought from
    BMW!

  8. #8
    Join Date
    Oct 2018
    Location
    New Jersey
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    My Cars
    1985 325e
    Okay I've become super lost now.

    I'm so close to doing it. Headset is in, everything connected, but the rear speakers arent working.

    Here is where I'm at right now
    Bought a kenwood bt522hd and the harness has these wires https://flic.kr/p/NXEvg8

    I know what needs to go where based on this post and this diagram
    https://flic.kr/p/NXEwge
    https://flic.kr/p/NXEx58

    It says theres a shared brown wire between the rear and front but the post has 2 brown per front and back

    What's confusing me is I have this setup.
    On the fader I have 3 yellow (y/rd, y/blk, & y) and 3 blue (bl/rd, bl/blk, & b) and then I have a separate set of wires of 2 yellow (y & y/brn) and 2 blue (b & b/brn).
    https://flic.kr/p/29XfPt1
    https://flic.kr/p/2cHS5j4

    What I wanna know is do I cut the fader wires (the black and red ones) and put them to the positives for forward and rear speakers, and then share the ground for both on the brown? (So y/rd + white, y/blk + green, y/brn + grn/blk & white/blk)

    Or are there 2 more brown wires I'm supposed to find somewhere in there to connect instead of having a shared ground. I reached around and saw that the bundle of wires weren't just heat wrapped but had a huge zip tie around them.

    Any help quickly would be appreciated, not a fan of driving to work with a stereo not in and with wires everywhere. Dont want anyone stealing my new headset.

    Thanks

  9. #9
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    Remove the fader. Use the fader in the head unit. Each speaker has its own set of 2 wires. The wires you want to connect the head unit to are the ones from the factory fader to the speakers. BMW sells a cover for the hole where the factory fader sits.

    Technically, there’s no “ground” wire for a speaker as each of the speaker’s 2 wires alternate between being positive and negative. Obviously 1 wire has a negative signal while the other has a positive signal. The polarity changes with the music.

    Google “sine wave.” Almost all energy flows as a sine wave.

    Nice head unit. It has lots of features.
    Last edited by MarcoZandrini; 11-07-2018 at 06:19 AM.

  10. #10
    Join Date
    Oct 2018
    Location
    New Jersey
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    My Cars
    1985 325e
    I understand the fader wires need to connect, i'm confused as to what to where. Everywhere says I need a brown wire for the rear as well.
    If I shared the only brown wires from the car (y/Brn, blu/brn) I would still have 2 solid yellows left over.

    From what I gather, the fader wires that have red are front and the ones that have black are rear, 2 wires for the blue, 2 for the yellow. My confusion is there is only one last wire from the fader for each yellow and blue (the solid)

    If I need to use only fader wires wouldnt there be more.

  11. #11
    Join Date
    Oct 2018
    Location
    New Jersey
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    My Cars
    1985 325e
    I've connected the fader wires to the harness but I still cant power the rear speakers. I cant find a second set of brown wires anywhere unless they are tucked way back. Also the wiring is zip tied and I cant find a way to cut it.

    So as of now my rear negative wires from the harness arent connected to anything but the positives are on the fader wires.
    When i connect them to the same negative as the front speakers the headset gets really hot and sound will only come from the front speakers so it's clearly not that.

    I tried the two solid wires that were with the fader but that just made the headset have a message like "Wrong Wiring please turn off" so it's clearly not those.

    Any further advice ?
    Last edited by 85moonboy; 11-07-2018 at 07:48 PM.

  12. #12
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    Oct 2018
    Location
    New Jersey
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    My Cars
    1985 325e
    I'm genuinely frustrated at this point. I have no damn clue where the other ground wires are to the rear speakers.

    My hands are too F'n big to move around to cut the zip tie harness in the car, I cant personally see any of the brown wires tucked back, and I'm lost. I plugged my ground wires into the solid yellow and blue wires that were from the fader even and no rear sound. (I read that in another forum)

    At this point I dont know if my rear speakers are just dead to begin with or if I genuinely cant find the wires and are just an idiot. Regardless I'm frustrated cause this is my daily driver and it's hard to work on this thing after work with no daylight

    Heres the annoying harness in there.
    It doesnt help that every single thread I read about this has different wire setups and what not.
    https://flic.kr/p/29YrH1y

    At this point I'm just completely exhausted of trying to figure this out.

  13. #13
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    2018 BMW M240i
    Get rid of the fader!!! You don’t need it. Connect the head unit's speaker wires to the car’s speaker wires. Period! Don’t make this more complicated that it needs to be.

  14. #14
    Join Date
    Oct 2018
    Location
    New Jersey
    Posts
    10
    My Cars
    1985 325e
    Didnt you say i needed to use those fader wires connected to the new headunit wiring harness?

    Because the only other speaker wires was a 2 pairs. And those wires only go to the fronts

    I cant find anything to connect the rears to and its driving me crazy.

    Unless my rear speakers are just dead, I cant produce any sound from them and I don't know how to check if they aren't dead

  15. #15
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    Originally, the speakers were connected to the fader in the dash. In reality, the factory head unit’s amp has only 2 channels-left and right. The factory fader split those 2 channels into 4.

    Simply connect the new head unit’s speaker output wires to the car’s wires that go to the speakers.

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