Radio Wiring and Amp Bypass

[def328]

Your car uses 1 signal ground wire from the deck to the amp.

If you want the easy way out, simply use the amp.

If you want a better way out, got a 4 channel or 5 channel amp...all your speaker wires are already in the trunk.

BTW: I know of a decent 4 channel amp for $50 new right now. Obcon brand, typical taiwan stuff, but sounds great. Look at this: http://www.speakerboxesusa.com/ob-2800i/

If you want to do the bypass, you get to run new wires. I say if you are gonna do that, I have a new-ish technique: do all of your connections under the back seat, up near the big grommet on the rear wall. All 4 pairs of speaker wires come through there, you can use the chart at the top of this thread to get your speaker colors there.

Lucky you!

Think I'm going to take the easy way and use the amp for now. I don't have the brown/orange wires either. If I did it this way which wire would I use for the negative for the head unit speaker wires?

Thanks.

[bimmer630]

Grab that 8 pin harness and start stripping the tape back until you get to the connections I referred to in my writeup.

Shoddy picture but its something. the connector has a few pins that just loop back around.

I found that the speaker grounds are the ones with the factory crimps, you can see one in the pic where the insulation came off the crimp.
Two brown wires come into two sets of twisted wires, which are Yellow/Brn and Blue/Brn. I dont know why BMW wired It up this way because these two sets of grounds go back to the factory amp and all splice into a single ground going into the amp connector. Why didnt they just run ONE ground wire back to the amp?
So anyway I hooked everything up as shown in the OP but my speakers crackle and it sounds terrible.
Common speaker grounds just dont work with aftermarket head units. I dont know how all you guys got your systems to work like this.
What I ended up doing is cutting the wiring at the amp and just bypassing the amp. I used trial and error to figure out which twisted ground wire was for which speaker, since theres four of them and only two different colors.
SO my Alpine is running into factory wiring, into factory premium sound speakers. It sounds pretty good.

[StereoInstaller1]

Next one of these I do (seems 2 or 3 a month) I will take pics. That is a mess, no reason for a mess like that. Start by cutting all the wires on the deck harness equal length, then cut all the stock wires equal length and taking out all the superfluous wires, like the ones that come from the deck and go to the fader.

"Common ground" DOES work PERFECTLY with ALL aftermarket stereos, IF you use it properly. If you follow my instructions, it will behave flawlessly.


Luke

[MC Hammered]

I am now starting to pick up alternator whine when I did not have it before.

Do you have any tips as to where to look for the problem?

[raleigh29]

Well everything works great, but all the speakers are crackling/popping when I get up into the Mid/higher ranges of volume. I figured that the speakers were bad, so I went out and bought some nice Pioneer 5 1/4" and installed those... SAME PROBLEM.

Do you all think I messed something up with wiring in the head unit? Regular JVC unit hooked up to my old premium sound in my 91 cabrio just as the diagram

[StereoInstaller1]

Nope, bad amp.

Bypass that thing, should be same wiring.

Twisted pairs back to the amp, twisted pairs out of the amp. Should be 1 to 1, except for the odd color codes.

Make sure there isn't a single ground point back to the amp, there should not be.

Luke

[raleigh29]

Nope, bad amp.

Bypass that thing, should be same wiring.

Twisted pairs back to the amp, twisted pairs out of the amp. Should be 1 to 1, except for the odd color codes.

Make sure there isn't a single ground point back to the amp, there should not be.

Luke

Yeah I bypassed the amp and removed it as per your post.. Maybe the head unit is a POS

[bimmer630]

I wired my stuff exactly like you posted.. And got the crackling speakers. Bypassed Amp and cut bac amp wiring enough to find the seperate grounds for each speaker, hooked it up that way and it sounds fine now.

[e30time]

Thank you for the write-up. I bought my first e30 (BMW for that matter) a couple months ago, and it had no stereo. Your pin out made installation about a thirty minute procedure, even though I don't have premium sound and the twisted pairs run from the dash directly to the speakers. Now I just have to get new speakers and want to do an amp.

One question you may be able to assist with... there was a non-twisted pair of wires wrapped together, one black and the other white or light grey, both solid. It appears from the wrap that they are original. Any idea what they might be for?

Cheers,

Blake

[Just Scott]

THIS IS FOR LATE MODEL, PREMIUM SYSTEM


I found this on another website and used it today to get my system working. It's just a cheap Blaupunkt Monterrey the PO installed and with stock premium speakers in a '93 convertible. The grounds are now separated and everything functions like it should. I'm hoping this fixes my battery drain problem too!

Basically, this takes the speaker wires from the dash/head unit and shows you the color codes to splice together in the trunk. I just cut them right off the amp plug. Took 8 crimps in the trunk (4 x +/-) and another 8 up front, plus the standard connections.



Amplifer Plug 'Pinouts' (Wiring Harness Colours)

The amplifer wiring harness plug has the following circuits: 4 channels of input from the head unit, 4 channels of boosted output to the speakers, switched power lead (activated by head unit), constant battery power lead, and power ground. Following are the pinouts on my car as tested and verified by me:

BETWEEN HEAD UNIT AND BOOSTER AMP

Yellow/Red - Left Front Channel
Yellow/Black - Left Rear Channel
Blue/Red - Right Front Channel
Blue/Black - Right Rear Channel
Yellow/Brown - Left Channel Ground at Amp End Only
Blue/Brown - Right Channel Ground at Amp End Only
Brown - All Channel Ground at Head End Only
(note that the all of the grounds are spliced together within the wiring harness - the system uses a common ground between the head and the amplifer)
White - 12V Switched (to turn amplifier ON when head unit ON, also runs to power antenna)

BETWEEN AMP AND SPEAKERS

Pair: Black/White and Black/Brown - Right Rear Speakers
Pair: Grey/White and Grey/Brown - Right Front Speakers
Pair: Black/Red and Black/Purple - Left Rear Speakers
Pair: Grey/Red and Grey Purple - Left Front Speakers
(note that the wires highlighted in red above all run to the crossover side of the midrange drivers, you'll want to know this to keep all your speakers in phase - make sure all of your speaker (+)s go to these wires)
(also note that the speaker circuits DO NOT use a common ground when they leave the booster amp)

[klavender1]

Forgive my ignorance, but I've read over these post time and time again. I think my ADD starts kicking in and it's hard for me to figure this out. :-D I apparently have the premium system in my 87 325e. Rear speakers have been changed by PO and I added the tweeters. It's came with the fader, amp, and 4 speakers. You're saying to bypass the amp and use the stock wiring I need to disconnect the wires from the amp and connect them to each other in the trunk? Matching left front channel wire going in, to the left front speaker wire coming out, etc? I just want to make sure I'm not missing something before I fry something. And I don't see the grounds tuck up in the fader harness. Just 6 wires coming out of the fader and going into the car. I peeled back the wrapping but it's just those 6 wires. I'm not opposed to running new wire just prefer stock wire per Stereoinstaller's suggestion.



I take it this is the amp?:

[801coppertop]

Thats not the amp... at least not in my experience. In my car that piece your holding is attached to the amp. Its a little longer, i have it sitting in the garage. When i get home from work i will take a picture of it and post it up.

[StereoInstaller1]

Forgive my ignorance, but I've read over these post time and time again. I think my ADD starts kicking in and it's hard for me to figure this out. :-D I apparently have the premium system in my 87 325e. Rear speakers have been changed by PO and I added the tweeters. It's came with the fader, amp, and 4 speakers. You're saying to bypass the amp and use the stock wiring I need to disconnect the wires from the amp and connect them to each other in the trunk? Matching left front channel wire going in, to the left front speaker wire coming out, etc? I just want to make sure I'm not missing something before I fry something. And I don't see the grounds tuck up in the fader harness. Just 6 wires coming out of the fader and going into the car. I peeled back the wrapping but it's just those 6 wires. I'm not opposed to running new wire just prefer stock wire per Stereoinstaller's suggestion.

[ATTACH]42910[/ATTACH]

I take it this is the amp?:
[ATTACH]42911[/ATTACH]

First that writeup is for LATE model cars, NOT yours.

Second, you don't have an amp.

[StereoInstaller1]

I just wish I had the skills to draw a diagram and show it on the computer...you guys kill me.

[klavender1]

I guess it would help being able to read it. Haha. It says "lampenkontrollgerat". Which I assumed is some sort of lamp control. And after googleing that and "Kennzeichenbeleuchtung" which translates to number plate lamp. So I have no amp. Easier to wire up then. Thanks!