Radio Wiring and Amp Bypass

[StereoInstaller1]

First, let me say this is NOT applicable to all E30s. Generally, Late Model (88+) will have this wiring on premium sound cars. IF you have a fader in the dash, this MAY work: you need to unwrap about 8" of fader harness to see if you have 4 pairs of speaker wires, as some cars have only 6 wires, not 4 pairs (8 total) so if this chart does not apply PERFECTLY to your car, don't use it.

Quick disclaimer: this is not idiot proof. You mess it up, don't whine at me, I do not care.

If this saves you countless hours of hassle or you are just feeling generous, feel free to paypal me a tip. Add "@gmail.com" to Stereoinstaller1 and I promise to only use the money for projects on my car.


OK, here is the info.

Obviously, what you do here is simple: connect the "deck" wire to the "dash" wire, then back at the trunk, connect that "dash" wire to the "speaker" wire.

This is not rocket surgery, boys. Get it done.



Aftermarket-----------Dash Wires-----------Speaker Wires

RF+ Grey--------------Blue/Red-------------Grey/White
RF- Grey/Black--------Brown/Orange--------Grey/Brown

LF+ White------------Yellow/Red------------Grey/Red
LF- White/Black-------Brown/Orange--------Grey/Violet

RR+ Violet------------Blue/Black------------Black/White
RR- Violet/Black-------Brown/Orange--------Black/Brown

LR+ Green------------Yellow/Black----------Black/Red
LR- Green/Black-------Brown/Orange--------Black/Violet


(+12V Unswitched) Yellow----Red/Green (Changes to Yellow at C302)

(+12V ACC) Red-------------Violet/White (Changes to Voilet/Grey at C302)

(Ground) Black---------------Brown (may also be Brown/Black)

(ILL) Orange-----------------Grey/Red (Changes to White at C302)

(P ANT) Blue-----------------White (this is one of 2 white wires)

(AMP REM) Blue/White--------White (this is the one in the same harness as the speakers)

Luke

[bimmer630]

I know I know.. Im being vague. My USB cable is giving me issues so i cant load pics.

Ok I found the amp hiding behind the antenna motor. I have no fader knob,

behind the "missing" head unit, I have an 8 pin connecter with:

- Yel/red
-Yel
-Brown/Blk
-Blue
-Blue/red
-Blue/blk
-Yel/blk
My head unit should work fine powering the speakers on its own, but I can also just run RCA's to the trunk, hook up my Blaupunkt amp, and tie into the speakers at the factory amp connector... but if i wanna add a sub in the future i would wanna use this same amp, sooo...
How do I connect to the rear deck speakers directly from the aftermarket Head unit without rewiring?

[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

[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?:

[StereoInstaller1]

Your '86 has 2 wires going to the fader, plus a ground. After the fader is a main ground splice, but it still only has 2 speaker grounds at that point.

There is a ground splice right by your left seat, but running wires from there is a hassle, easier to use that pair of grounds as the rear grounds and re-wire the fronts completely if you want a simple way of dealing with it.

[klavender1]

Your '86 has 2 wires going to the fader, plus a ground. After the fader is a main ground splice, but it still only has 2 speaker grounds at that point.

There is a ground splice right by your left seat, but running wires from there is a hassle, easier to use that pair of grounds as the rear grounds and re-wire the fronts completely if you want a simple way of dealing with it.

Thanks! Just now saw your post after I got everything put back together.I used the wiring diagram posted on here. I wired up all the speaker positives from the HU to the positives going to the fader. Then shared the grounds. So left speakers' grounds on the HU to the left speaker ground coming from the car harness, and vice versa. Do you think that will be an issue? It all works and sounds better. Otherwise, it's hot outside. :D

[racerjay88]

Luke,
So I read this entire thread and I tackled an install in my '87 eta. Head unit is Sony Explode (don't have model number in front of me) and 4 brand new Kenwood 4" at all four corners. I followed the wiring advice at the top of this thread and it worked for the rears sort of. Since I only have 2 pairs of wires coming out of my fader in the dash I used those two pairs as the rear left and right positive and negative. I then ran new wire for the front and they work fine. Have not completed the install yet (head unit is not mounted in dash) but wiring is done at the trunk with an Amp bypass and the Sony wiring harness is spliced to the BMW for power and such. I have one question now. I have no volume in the driver side rear speaker (Left rear) Pass side speaker has volume and appears to be working. Where should I start checking my wiring at the trunk Amp bypass bundle? Any suggestions?

[StereoInstaller1]

Ok I figured I was just reading something wrong.

I did get mine figured out, I just found the grounds for each speaker using process of elimination, that was before looking to see if the proper speaker positives were twisted with a ground.. I dunno if they were, I read that part after I got mine going.
So yeah I bypassed the amp, Im back on this thread because I have a 90 Vert at the shop the guy wants a stereo, and I needed a refresher course on how this is done.


Thanks for all the info

If it has a fader in the dash it will be the "more hassle" version where you use the 4 positives to run the rear speakers and run new wires for the fronts...otherwise, you will have 4 twisted pairs in the dash that run back to the amp, where there are 4 more twisted pairs to connect to.

[airkhin]

I have an 05/87 build date m3, i tried to follow the wiring to see if there were splits for the grounds... no juice... the po had a after market deck hooked up to the oem fader switch for some reason?

i tried to find a wiring manual but am having some issues finding the exact one by color codes of wires that i got... looking to bypass the amp in back and get all speakers grounded normally so no more whining...

even with the whining of the speakers, the luke box sure does wonders!!

[Miasma]

Just got done rewiring my 87 IS. Had a stock amp with premium sound WITH a fader. Sounded like shit, Took a while and had to run new wires for the front lows and highs, But sounds AMAZING now.

[thedivision]

I just connected my stereo in an 87 325 (not i) with the fader switch. I didn't have any individual negative speaker wires going from the dash to the amp (common ground system). Not at the dash harness, not at the amp harness.

I connected the 12v constant, switched, ACC, thick radio antenna.. those are pretty standard. I had 4 available positive speaker signals, which I spliced before the fader switch: blue/red, yellow/red, blue/black, yellow/black. I connected these to positive wires coming out of my deck and left the negative wires unconnected.

I connected the accessory turn on wire coming out of the deck (blue/white for me) to the white amp turn on wire. I left the white antenna wire in the dash disconnected since my antenna doesn't work.

I tried using the pre-amp signals (RCAs) instead but the sound was very quiet. I will eventually run 4 wires for each ground to the trunk and bypass the stock amp altogether, I just didn't have the time today. The sound is effectively being amplified twice right now.

Hope this helps someone.

[Gubernaculum]

Here's my solution for my '87 325is with premium sound - it doesn't have the same fader switch (with + and - to each speaker) mentioned in the first thread so it's slightly more involved:

Step 1 - get the Electrical troubleshooting manual for your year/model. It's online. It's free. Print out the appropriate 2 pages. If you skip this step you are really dumb.
Step 2 - everything else.
To bypass the amp You need to run new wires to the front speakers and re-purpose the wiring to the amp/rear speakers so you don't have to run all new wires to the rear. Keep track of your polarities according to the "Speaker wire color" list in the original post.

Fronts:
Left +: Cut the gray/red a few inches from the connector at the kick panel speaker and run your positive to that. the other end of the gray/red is coming from the amp. it's dead to you now. Leave it dangling.
Left -: Splice your negative INTO the gray/violet. I cut the wire a few inches from the speaker connector, stripped both sides, and put both sides into one side of a blue butt connector. I put my new speaker wire negative into the other side of the butt connector. Yes, a long section of wire coming from the amp will now be dormant, but I didn't want to track down where the splice connector was. Besides, Electricity, like the honey badger, don't give a shit. You'll see what I mean when you look at the wiring diagram.
Right +: Positive to the gray/white as before.
Right -: Negative spliced into the gray/brown, 3-way style, as before.

Rears:
Basically you're re-purposing the 4 wires that go from the fader to the amp and instead using them as speaker wires. They're Yellow/black, yellow/red, blue/black, and blue/red. Re-Assign them to be your Left rear +, LR-, RR+, and RR- however you see fit, but write it down. These 4 wires go into the amp, which spits out 4 wires to the rear speakers (which you'll use) and 4 wires to the front speakers (which are now dead since you ran new wires to the front). So, you use your butt connectors to jump the 4 amp input wires to the appropriate 4 amp output wires going to the rear speakers. voilla! Instant speaker wires from the fader to the rear speakers, ready to go.
Left rear +: black/brown at connector position 7 (see the tiny numbers on the face of the connector to the amp)
left rear -: black/violet at 1
right rear +: black/white at connector position 5
right rear - : black/brown at pin 4. Note there are a couple black/brown so look at the numbers.

Good luck. Recheck my work before you do it yourself.

[alloydix]

I have a 88 325ix. It has tweeters and a fader in the dash.

The wires back at the amp.


The wires up front. This is back a little ways so all the loops are eliminated. I believe the green and red wire is a hot battery wire, and thus it is not showing in the back.


From what I see it looks like I need to re-wire, but bimmer630 seems to have done it with a situation that originally looked like mine (no orange and brown wires). I went back on the amp wires about a foot and a half looking for the individual grounds for the each speaker. I didn't see any. Should I go back further, or do I just not have them? Just Scott doesn't say anything about tying in negatives to the speaker wires, but from what Luke is saying that seems necessary. Thanks for the help guys.

I'm a noob to forums and had an issue last time posting pics. In case those didn't work, here are the links
http://www.flickr.com/photos/71254823@N05/6443620731/
http://www.flickr.com/photos/71254823@N05/6443622887/

[Eddie Haskell]

89i model with non premium sound no fader and never jacked with bone stock HU. Wired via Luke's synopsis. The 9v battery and testing the speaker leads did the trick. Pulled kickpanel on left side and voila the twisted pairs for rears and left side were there. Had to strip back factory harness behind HU and found the twisted pair leads. Snip,snip,snip and snip. Confirmed with the 9v before hookup. Job done in 1hour. 9v battery tool removes any question before going to the crimpers.

[mikeb23ft]

This is driving me nuts. I have a JBL Arsenal that I'm trying to install in place of the 1996 crappy aftermarket CD player that someone put into my car.

It is a premium sound 1988 325is with 4 pairs of wires into the fader and an amp in the trunk, but the wires aren't the same colors as the ones mentioned in the OP. To complicate matters the previous owner cut 4 of the wires coming from the fader and connected them to the old head unit. The fader oddly still worked with the new head unit installed. The wires in the trunk are the right color for the speaker wires but there are some other randomly colored wires just hanging out. I might need to seek professional help with this...