Early e34 Sound System Refresh - Stereo, Amp, and Speaker Install

[mostly amazing]

I need some help making sense of what I am looking at in my 89 535i. For some background, I've been reading the helpful threads about upgrading the sound system:

https://www.bimmerforums.com/forum/s...speakers/page2
https://www.r3vlimited.com/board/sho...d.php?t=288210
https://www.bimmerforums.com/forum/s...=common+ground
https://www.bimmerforums.com/forum/s...=common+ground
http://www.bimmernut.com/forum/showt...s-for-dummies?

Removing my factory deck, I am faced with the jumble of wires that everyone mentions. Since this is an early e34, there is no harness to use. I have noted the rear and front speaker wires, power/ignition, dimmer memory, cd changer, and ground bolt-on thing as indicated by Stealyeye's thread. However, I cannot figure out what this red wire is:

https://drive.google.com/open?id=1Lp...mJib47P2hJwpKD

It did not come from the stock head unit, so should I just disregard and tuck it back in? Also, pulling my rear seats, I see that there's what appears to be a red power wire running from my battery:

https://drive.google.com/file/d/18Wb..._mjwNHBb6M_mC_

Also I noticed unplugged harnesses next to my battery, does anyone know what these are for?

https://drive.google.com/file/d/1PN2...Si8wI3XYssyiQb

If you are wondering, I am hoping to follow this diagram I created to set up my new sound system, do you think it is feasible?

wiring-proposed.png

[moroza]

That red wire is not stock.

The trouble with early E34 audio is that it's a common ground system. Some headunits play well with it, others require fading full forward or back, and others might not work at all or give poor sound output.

My solution was to run eight new wires (+ and - x4 channels) between the amp and the headunit, remove the crossover board from the amp, and solder those eight wires to the crossover. Speaker wiring can remain as is, and I suppose you could just run four new wires for individual grounds. The car I did that on is long gone and I have no photos unfortunately. IIRC I twisted the eight wires together to reduce interference, and routed them by the driver's rocker panel. If I did it again I'd send them up the center console above the driveshaft hump.

[mostly amazing]

I followed the red wire and it turns out its for the alarm system the previous owner installed. I'll probably pull it out at some point since the alarm doesn't seem to be working. Additionally, I found this:

https://www.ecstuning.com/b-genuine-...r/65129410558/

which appears to the ke83zbm harness. I am debating whether or not to buy it, so if anyone has used it before, let me know how you did it with your install. I've tagged and ID'd all of the wires from inside the dash, but have not looked at the wires at the stock amp input/outputs.

Moroza, thanks for your reply. I am trying to avoid having to run new speaker wires to and from my aftermarket amp and aftermarket speakers. Tucking all of the wires appears to be a pain, and I looked at the dash area and can't see a way to get wires down towards the center console. What was your technique to get your wires into the cabin from behind the dash? How did you run your wires back to your speakers from your amp?

As I see it, if I address the common ground issue via Luke's "hack" (splicing positive front R+L and rear R+L into the head unit harness while taping off the negative wires and grounding them), I should be able to use the existing wiring loom. Again, that is if I can ID the wires on the input side of the stock amp and run a line out converter in the trunk. I need someone who knows a thing or two about this to tell me if my diagram above is feasible.

[moroza]

IIRC I ran them through the trunk somehow (found a hole to punch out? I can't remember), up the C-pillar behind that trim panel, above the headliner near the driver's side grabhandles, down the A-pillar, and behind the gaugecluster. Doing it again, I'd run just four wires (new negatives; there are already four positives): get them under the rear seat somehow, peel the rear carpet forward to reveal a black plastic tunnel, stick them in there, have them emerge from under the carpet roughly at the hazard switch, under the shifter, and up behind the ashtray.

I understand E34 and auto wiring pretty well, but audio wiring (RCA?) not as well.

[summitp]

If you plan on replacing the factory amp, and the factory head unit? Why would you not just run RCA from the head unit to the amp in the trunk?

Also, I can't comment necessarily on the older model speaker wiring, (mine is a 95) but the wiring to the speakers from the factory amp worked fine for me. I used the factory wiring for all 6 front speakers from an aftermarket amp.

[mostly amazing]

Well, the thing is the head unit I've chosen, the Continental TR7412UB, does not have RCA outputs. I think the aftermarket amp I've chosen already does this, but I'm going to use a line out converter in order to control the line level issues from the head unit. If you've seen the Continental TR7412UB, it's the bee's knees and I've already had Earthwormjim mod the unit per this thread:

https://www.bimmerforums.com/forum/s...t-on-E36/page6

I've resisted running wires to the aftermarket amp from the dash directly, because I don't want to tuck the wires and do what Moroza has suggested above. Just reading the part about "peeling the rear carpet forward" makes my hands clammy. I was hoping to avoid doing that by using the existing wiring in the car, and following the "common-ground-wiring-splice" instructions that some folks have done. But I get what you are saying, and at this point, I might as well run new wires to the aftermarket amp, and use the existing wiring from the factory amp outputs to send the signal to the speakers as a compromise.

Yes, I probably should just run new speaker wires. Yes, I probably should use a head unit with pre-amp outputs. But dammit, this Continental head unit looks awesome.

[summitp]

I don't really understand the appeal of that deck beyond the fact that it looks somewhat oem. If you are going to run a head unit without RCA outputs to a line level converter, would you put the converter somewhere in the dash area? If so, you need to run RCA anyway. If you put it in the trunk, you should probably run wires to have grounds for each speaker, so might as well run all new speaker wires back, in which case you might as well run RCAs anyway. After you add power, you might decide that you need to eq, etc...

[moroza]

The carpet thing is really no big deal. If you can remove the rear seat bottom, you can handle the rear carpet. Now, the front carpet is another story...

[summitp]

One thing you could do, if you could make it all fit somewhere, is put the amp up front too... Something small like this...
https://www.crutchfield.com/S-kA4VXs...waAqSKEALw_wcB

Plug those RCAs into the back of the head unit.. oh wait... But anyway, a small amp ought to fit somewhere up front so you don't have to run wires.

[mostly amazing]

One thing you could do, if you could make it all fit somewhere, is put the amp up front too... Something small like this...
https://www.crutchfield.com/S-kA4VXs...waAqSKEALw_wcB

Plug those RCAs into the back of the head unit.. oh wait... But anyway, a small amp ought to fit somewhere up front so you don't have to run wires.

Gotcha. That might be the path of least resistance, but I'd still like to try to use the existing factory wiring loom before running my own wires.

As for the line out converter (LOC) in the trunk vs the dash, that is something I need to check the factory amp wiring to see if it can go in the trunk. The LOC needs +/- inputs in order to output to RCAs. If the factory wiring loom has +/- wires running into the factory amp inputs, I should be able to put the install in the trunk. If I am correct, as-is, there are no factory negative wires in the front dash that were connected to the ke83zbm, so LOC in the dash is a non-starter if I use the factory wiring.

If I can use the factory loom, the LOC and amp will go in the trunk. If I have to run my own wires, I'll take your advice and run it in the cabin.

[moroza]

Wouldn't putting the amp up front mean running 20 new wires to the speakers?

[summitp]

Well, my advice is run RCAs to the trunk, and put a 5 channel amp back there, and use factory speaker wires.
Sort of like this...
IMG_20190214_173406.jpg
IMG_20190214_173356.jpg

[mostly amazing]

Well, my advice is run RCAs to the trunk, and put a 5 channel amp back there, and use factory speaker wires.
Sort of like this...
IMG_20190214_173406.jpg
IMG_20190214_173356.jpg

Thanks for the images. Are they yours? If so, did you recall if the input side of the factory amp have negative wires?

Moroza, it'd just be 8 wires since I am not using a component system, but 3-way speakers in the front and rear.

[summitp]

Pics are mine. Someone else yanked out the amp, so not sure on factory inputs for mine. The e34 Facebook group has a file section where you can find the wiring diagram specific to your car.

Don't forget, key to not getting any engine whine or interference is running power for your amp away from your signal wires to the amp. If they must cross, do so perpendicularly.