Radio Wiring and Amp Bypass

[6670charger]

If you didn't have twisted pairs, how did your back speakers ground? I can see how running new wire to the front might make a ground for the front speakers, but, don't they all need to be grounded?

Sorry. I'm an electrical novice. I know the basics, and just enough about wiring to get myself into really big trouble. This is why I was hoping to get away with using the factory wiring. It's already there and run to where it's supposed to be, and is supposedly really good wire. I just need to know how to ground the speakers, as the only wires I've found for them so far are the positives. I'll unwrap some more of the harness to see what I find, but based on what I've seen so far, I have a feeling it's going to be nothing more than what I have unwrapped right now.

I'll have to say that the E34s I had in Germany were a heck of a lot easier to work with for stereo wiring. Those cars actually have a harness adapter for them that is completely plug n' play.

[MrDomino]

I'll give that a shot, however, just looking at what's exposed through the tape as it goes back, it doesn't look like the wiring changes any for quite a ways. I hope it doesn't turn to twisted pairs way up inside the dash or I'll never get my hands in there to work on the wiring.

Also, I don't plan on disconnecting the amp at the back right now. Guess I'll have to wait and see how things sound before I decide for sure.

I didn't have the twisted pairs either and just decided to remove the amp since I couldn't get it to work with the amp. See the image I just posted a few days ago that shows how to wire up the speakers without the amp. Trust me, it'll go much smoother if you just scrap the amp. All you need to do for your situation is remove both front kickpanels and then run new wires to the headunit for the front two speakers.

[mikracer]

An aftermarket head unit should power the factory speakers just fine. I had a few BMW's of this vintage in Germany the past couple of years. All of them had aftermarket stereos, and the stereos powered the speakers with no problems. In fact, the unit I'm installing I brought back with me. It's a JVC unit from a few years ago.

Thanks!

And just to clarify, does wiring this way (from post #1) bypass the amp? It says something about connecting the wires in the trunk, which leads me to believe it does, but then are you running new wires to run the front speakers? I'm a little bit confused.

[6670charger]

^You still have all that black tape wrapped up. Did not peel far back enough. Follow the positives back for each speaker it should be in twisted pairs. I had a newer model premium and the twisted pairs were definitely there. They joined into one of the brown wires as they got closer to head unit and connector.

Yellow/red+ driver front
Yellow/brown - driver front
Yellow/black+ driver rear
Yellow/brown - driver rear
Blue/black + pass rear
Blue/brown- pass rear
Blue/red+ pass front
Blue/brown- pass front

One comment to make is Luke has all the speaker negatives as Brown/Orange on the 1st page. That may be confusing because I know on mine the negatives had their own individual striped colors. They were not all brown/orange.

I'll give that a shot, however, just looking at what's exposed through the tape as it goes back, it doesn't look like the wiring changes any for quite a ways. I hope it doesn't turn to twisted pairs way up inside the dash or I'll never get my hands in there to work on the wiring.

Also, I don't plan on disconnecting the amp at the back right now. Guess I'll have to wait and see how things sound before I decide for sure.

[6670charger]

An aftermarket head unit should power the factory speakers just fine. I had a few BMW's of this vintage in Germany the past couple of years. All of them had aftermarket stereos, and the stereos powered the speakers with no problems. In fact, the unit I'm installing I brought back with me. It's a JVC unit from a few years ago.

[mikracer]

Will an aftermarket head unit power the factory premium speakers well? And will this wiring maintain all speakers working? I have an '88 325is with the premium stereo.

[CB-M3]

^You still have all that black tape wrapped up. Did not peel far back enough. Follow the positives back for each speaker it should be in twisted pairs. I had a newer model premium and the twisted pairs were definitely there. They joined into one of the brown wires as they got closer to head unit and connector.

Yellow/red+ driver front
Yellow/brown - driver front
Yellow/black+ driver rear
Yellow/brown - driver rear
Blue/black + pass rear
Blue/brown- pass rear
Blue/red+ pass front
Blue/brown- pass front

One comment to make is Luke has all the speaker negatives as Brown/Orange on the 1st page. That may be confusing because I know on mine the negatives had their own individual striped colors. They were not all brown/orange.

[6670charger]

I'm having a problem identifying what else I need to hook up for my car. I have an '88 325i convertible with what I think is premium sound (based on what PO told me), but I don't know for sure. The car does have a fader in the dash. I've stripped harness back about a foot from the fader as instructed in other threads, and found all of the wires as someone else listed below:

CD player colors ......... BMW wiring colors
Yellow (12V battery) ......... Green/Red (12V unswitched)
Red (12V ignition) ......... Purple/White (12V accessory)
Black (Ground) ......... Black/Brown (Ground)
Green (Left rear positive) ......... Yellow/Black (Left rear)
Purple (Right rear positive) ......... Blue/Black (Right rear)
White (Left front positive) ......... Yellow/Red (Left front)
Gray (Right front positive) ......... Blue/Red (Right front)
Blue/White (Amp turn on +12V)

My problem is that the speaker wires (far right colored wires in the pic) aren't in twisted pairs. The only speaker wires that exist in the harness are the colored positive ones listed above. There are two BRN/BLK wires; one goes from the factory deck to the fader, and there is one additional BRN/BLK wire that goes into the harness along with the speaker wires. I have no idea which wires, if any, are the ground wires for the speaker wires. I could strip and hook this up in minutes if I only knew how to ground the speakers.

Also, I assume the big thick WHI wire coming out of the left end of the stereo opening goes to the factory amp? I don't plan on hooking that up to anything based on what I've read so far.

[Quinthirty]

Thanks, Luke. I'll work on it over the weekend...

[StereoInstaller1]

The car has a bolt in rollcage and a completely gutted interior (no back seats) or anything in the trunk so it's pretty easy. Getting to the kickpanels is actually quite difficult with the rollcage. As for anyone else I'd recommend rewiring the front speakers and then just hacking up the wiring in the trunk for the rear speakers.

Agreeed! Run new wires to the rear speakers!

[MrDomino]

The car has a bolt in rollcage and a completely gutted interior (no back seats) or anything in the trunk so it's pretty easy. Getting to the kickpanels is actually quite difficult with the rollcage. As for anyone else I'd recommend rewiring the front speakers and then just hacking up the wiring in the trunk for the rear speakers.

[StereoInstaller1]

Yes, you can do that, but if you are going to bypass, it is easier in your case to run new wires to the front speakers and "re-purpose" the wires to the rear, using all 4 positive amp input wires to run the rear speakers.

That way you only have to take apart your kickpanels, no seat pulling required.

[MrDomino]

I just wired up the left rear speaker without the amp and it works great. I'm going to update the image to reflect what my final wiring is. I haven't actually tested this completely yet but it works on one speaker so I can't imagine why it wouldn't work on the other three.

[MrDomino]

After thinking about it some more I think it might make sense to just bypass the amp. I'm going to test it with one of the speakers tonight.

Just to be clear. I'm going to disconnect the amp and then connect the positive and negative wires for the left rear speaker to the yellow/black and yellow/red wires that run to the front of the car. I'm then going to connect these to the green wires on the new stereo. That way the stereo should be running directly to the one speaker.

If I do get sound out of the one speaker then I'll go ahead and rewire the other three speakers.

StereoInstaller1 can you take a look at the new stereo I'm installing and let me know if you foresee any issues wiring it directly to the speakers? I'm thinking that the amp is messing things up and that a direct connection to the speakers will work the best.

[MrDomino]

Here's the guy I'm trying to hook up.

http://www.bossaudio.com/auto/car-digital-media-am-fm-in-dash-mp3-usb-sd-aux-612ua/