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BMW E30 325ix Audio Disaster!

Discussion in 'E30 (1984-1993)' started by Tyjosimo43, Feb 15, 2018.

    Tyjosimo43 guest

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    Hi!, this is my first ever post on the CCA forum. I have just purchased a FANTASTIC 325ix from 1988 and have loved it so far. Except for one thing... The stereo! The car came with a totally toasted Sony that was working fine, and sounded fine. When I decided to change the stereo, I pulled it out and stripped all the wires back soldered them and nothing. So I go onto various forums and try and find out whats goin on and oh goodness it only got worse. Turns out I have a Premium Sound System and absolutely nothing about the wiring is standard. I have the power to the new head unit working and that is it. I found a great diagram as well for premium sound system owners out there and all the colors I have are in accordance to the diagram. Alright, here is what I have done and also what still needs fixing...

    Done:
    - Wires stripped back from fader
    - Identification of 12v Constant and 12v Accessory and successful powering of the new headunit
    - Identification of some of the speaker wires?

    Need Help:
    - What wire goes where when it comes to speakers, I have learned that there was only positives but will that even work with a modern headunit like the one I am trying to put in?
    - What is with the 2-3 ground wires (brown) Should I connect the headunit negatives to these or just tie them up and out of the way?
    - How do I know if the amp is working? I am getting absolutely no sound so perhaps a amp fuse is blown or something?

    I REALLY don't want to have to rewire the car. But If I can be convinced it is the only way, I might do it. I'm getting pretty frustrated at this point.

    Thanks to anyone that can help...
    [IMG]

    Attached Files:

    • Member

    MGarrison

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    Let's see... depends on how much you want to get into, I suppose. The simplest hookup is using the existing wiring. Obviously it's a bit of a task to be trying to run speaker wires through the car. With door-mounted tweeters, running wiring to that means pulling the door panels & plastic water-intrusion sheeting on the doors (& putting it back), & the kick panels, to run wiring to & up through the doors to get to the tweeters, plus whatever it takes to get stuff run underdash, and then there's getting wires to the rear speakers. You get into pulling the retaining plastic trim pieces along the door edges (& being careful not to break those), plus the rear side panels, etc. to route the wires the way the wiring harness goes, or removing the center console if you want to try to snake them along the trans tunnel, &/or pulling the seats to get under carpeting, etc. Probably a good route to go is start by what you're doing - see if you can get your head unit to work in conjunction with existing wiring & booster amp, & see if you're happy enough with the sound for that to serve your purposes.

    The E30 radio doesn't have the conventional 4-channel speaker outputs, instead somewhat oddly opting for only L & R outputs from the radio, to the fader which splits those two inputs into 4 positive-only (+) outputs to the booster amp, with the whole system using the chassis as a common ground. The particular downside to that is beside additional wiring hassle for a modern-day head unit, there's an increased possibility of noise, stuff like alternator &/or ground hum, etc. But, it's worth a shot to give the easiest a try for starters & see what you get from there.

    Here's the etm for your car, see section 6500 for the radio (not in color like above; if that doesn't bring it up, try the link dropping the 1988, etc. text & then scroll and select your car.

    http://wedophones.com/Manuals/BMW/1988 BMW 325ix Electrical Troubleshooting Manual.pdf

    This may be helpful but is specific to E28, although I think consistent w/ the E30, although I don't think it's specifically mentioning the wire to trigger/power the E30's booster amp.

    http://www.bimmerboard.com/members/vtbimmer/BMW_stereo.htm

    Assuming the above link is correct (sorry, this stuff is so far back in the memory banks I can't confirm it is, although you could try it twisting wires together or alligator clipping together before soldering to test), you can connect your head unit's pos. (+) leads to the 4 pos. leads exiting the stock fader thusly:

    Head Unit:

    Right Front (+) to: Blue/Red
    Right Rear (+) to: Blue/Black
    Left Front (+) to: Yellow/Red
    Left Rear (+) to: Yellow/Black

    You'll have to combine grounds - assuming correctness again:

    Right Front (-) & Right Rear (-) to: Blue/Brown
    Left Front (-) & Left Rear (-) to: Yellow/Brown

    However... looking at your diagram & the ETM diagram, it appears there's only one ground wire exiting the fader, a Brown/Black wire; if that's the only ground wire you have, then try running all of your head unit's four neg. channel (-) outputs to that.

    If I'm reading the ETM correctly, the white wire triggers the antenna to raise, AND the booster amp to turn on. If you connect whatever wire your head unit has for an electric antenna to the white wire, that should cover that. The 2nd link mentions the BMW radio puts 12v to this, fwiw - seems like high voltage to me, but I can't claim to be an electronic genius to explain why, or if, that's an appropriate voltage. I'm pretty sure the Alpine I put in my E30, I ran it's antenna trigger lead to the white & it worked fine.

    It would appear the Gray/Red is the dimmer, so that would go to your head unit's dimmer lead, assuming it has one.

    The wiring diagram you show & the ETM appear to be consistent, Violet/White is the switched-power lead, so that would go to your head unit's lead for that (hot when ignition is switched to accessory, run, or start). The 2nd link lists it as Purple/White.

    That leaves a lead for hot at all times, which you say you've identified, and your diagram & the ETM have that labeled as Yellow.

    If you have some spare wires to use for testing, it might be worth taking the time to run leads for testing the hookups before soldering your head unit's wire harness on to existing wires in blind faith.

    With this, your head unit's stereo outputs are going into the booster amp, and it's the booster amp providing the amplified sound - you'll have to decide for yourself if it's adequate for your listening purposes. I would say it works, and is generally ok, but if you're picky about sound quality, this system was ok in it's day 30 years ago, and I don't think anyone ever considered it stellar, except perhaps in comparison to what was in even earlier BMW's. The next step would get into bypassing the stock booster amp and connecting the corresponding input/output wires, but, that probably doesn't help sound quality much without dedicated neg. (-) leads for at least the rears, never mind the front kick panels & separate tweeters. And, if one were to go that far, you have to consider the quality of the stock speakers themselves, which is only so much. With the booster amp pinouts your diagram has, that would make it easier to figure out how to tap into the neg. (-) leads in the wiring harness exiting the booster amp, but I think you'd still have to look at the speakers and see if they have both +/- leads connected, or just +. If the tweeters, for instance, have only one wire connected to them, then the chassis is acting as the neg (-). Even going that route, the stock wiring, as very small gauge wire, is a limiting factor - hardly optimal for carrying a high-quality sound signal. If you get into further disassembly, some of the stuff here may be useful -

    https://www.bmwtechinfo.com/repair/main/561en/index.htm

    This may also be helpful, see Paul's last comment in the thread. I haven't had a problem blowing the fuse with the Alpine I put in mine, but his suggestion to run a dedicated power wire is not a bad idea, although it adds more work vs. just tapping into the existing wires. Again, if you get it working, you could try it first, & then go that route if needed.

    https://www.bmwcca.org/forum/index.php?threads/e30-wiring-diagrams-radio.2708/

    Hope this helps - seems like I wrote up stuff about this back with the club's first forums, which are no longer extant... hmmm, mebbe I should go see what's left of that on the internet database; the forums' first couple of iterations got nuked, unfortunately, with website & forum re-do's, this forum salvaged posts back to 2008.
    Tyjosimo43 likes this.

    Tyjosimo43 guest

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    Wow, yes this is fantastic help! Yes, I have been basically been trying to learn all this information from various forums across the web to no success, no wires seemed to match, everyone had different solutions and then of course there was that one fellow that simply replied... "Ah yeah, just rewire the car". I really want to do some sort of write up about it once I finally tackle it. Seems like a TON of people with premium sound struggle with aftermarket units.

    I got to experience the sound system for about 15mins before the old headunit fell apart (it was in shambles and required a couple firm taps on the face for the connectors to line up) and honestly I found it to sound pretty good, I thought it was pretty impressive for a 30 year old car. I love listening to some 80's rock in it.

    I was unaware that the Antenna and the amp power was connected to the same thing. I figured there would be some sort of trigger but had no idea which wire and didn't want to send a bunch of power to it out of fear I could fry the AMP. I theorized that the AMP was totally off because there was not a single sound, not even any static.

    I'll make sure to let you know how it goes. Once again thank you for the very VERY detailed response. I really love how this community can get together. :)
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    MGarrison

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    Good luck with it - deciphering the wires is the confusing part, once you know which is which, the hookup's pretty straightforward. For the amp, as I mentioned, that's on the assumption I'm reading the etm correctly - 6500-0 indicates the white wire going from the radio, but splits, with one branch going to the antenna as the raise/lower trigger, and the other branch (the "A" in the black triangle) continued on 6500-1, and there shows it running to the booster amp. Since the etm shows both the antenna & booster amp as having fused 'hot-at-all-times' wires, since the white wire is switched w/ the radio & triggers the antenna to go up, I figure it's logical it's also the on/off trigger for the booster amp. Checking w/ a voltmeter would confirm that, but as I mentioned with my aftermarket head unit, putting it's power-antenna lead to the white wire seemed to work just fine. When you get a chance to check out those etm pages for the radio, you'll see what I'm talkin' about. :)
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    MGarrison

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    The four pages in the ETM radio section after the wiring diagrams have diagnostic tests, a number of things to try there. One mentions installing a dedicated ground strap to the radio. It's worth checking the other ground straps on general principles, you might find the one from the hood to the nose panel &/or the one off the engine block is/are broken. There should be a ground strap/wire from the antenna, you have to pull the left-side trunk cover panel to check it out. In any case, the diagnostic tests might help make some headway.

    High volume - I wouldn't be surprised if that's speaker distortion from not being able to handle the volume level, or the booster amp itself distorting, but that's just a guess.

    No clue why all neg (-) head unit leads connected to the ground wire would cancel the sound. I'm no electrics/electronics/sound engineer expert or anything like it, but without taking time to google, I'd figure the way a speaker makes sound, the ground remains a constant voltage, and the pos (+) varies voltage. If that's the case, perhaps if a speaker lead outputting the pos (+) signal were crossed to ground, it would cancel out the other signal across all three with the common ground setup. But, that's a guess, although the simple check there is make sure the right head unit wires are going to the right wiring harness wires. Otherwise, puzzling, no clue! Might be worth searching on mye28.com, lots of expertise over there, and similar vintage late 80's 5ers would have had similar radio wiring & setups, if not identical. Double-check your wires & verify their color combos? You mention connecting neg (-) speaker leads to "a ground"; if it's the brown/black wire exiting the fader, I'd be thinking that's the correct one to connect to, as opposed to grounding to something else.

    Tyjosimo43 guest

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    So it has been a while and I have made tremendous progress. So I had two brown ground wires that came out in the dash and I simply decided to attach them to one another and voila the volume issue was solved, perfectly clear and wonderful sound. I cried happy tears... Then I turned the engine on...

    Alternator interference. I know exactly what it is but am uncertain what can stop it. One thing that I will note is the fact I have a very cheap headunit, I think this is the problem but don't want to drop cash on a new one because I have a great idea for a PERFECT headunit in the future (An Arduino headunit inside of a OEM faceplate that adds AUX and bluetooth and all the modern features we so desire with the perfect OEM look.) but that will obviously take a while. So looking for something to fix it in the meantime! Thanks.
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    MGarrison

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    Go back to the ETM, it explains the diagnostic tests with solutions to try for alternator noise. Glad to hear you're getting sound!

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