Radio Wiring and Amp Bypass

[randomtask37]

^^^ that is a nice addition.

im not sure if its right, but if it is im sure it would be helpful for an installer.

[CB-M3]

The posts I'm reading about using stock wiring and common ground system was causing problems for people on premium sound. People are running all new wiring to each speaker for better results. Just getting conflicting info so don't know which direction to go for my install. After I get mine working I will post more install pics to add to this thread.

So for my setup below I only have a LF+ and RF+ (No LF- and RF-). Do they come together as 1 Ground back in the trunk area as a common ground? I'm going to take out the trunk lining tomorrow to see if I even have an AMP and what wires are going In and Out. Also noticed the wiring harness provided by the Pioneer head unit has really small AWG wire. Nowhere near the stock wiring size.

[StereoInstaller1]

Oh lord, I really do get tired of explaining this.

E30s are NOT common ground.

Post your year and model AND what stereo came in it stock, R3V will help you figure it out.

For example, that looks to be a late model, non premium wiring.

See where the brown wire twists with the blue or yellow? Unwrap that harness about a foot, you will see where all of the wires become twisted pairs, one pair per speaker.

From there, it is pretty easy to figure out which is which, just remember that the black stripes are positives for the rear speakers.

If you have premium sound, you will find an amp in the trunk, just in front of the antenna, on a bracket with the check panel diode pack. Don't fuck with the check panel wiring, you will regret it.

Luke

[CB-M3]

i have the premium sound deck and tweeters but no premium wiring? that's odd.

I have a 1991 318is, no fader, Head Unit is CM5908. It has rear premium speaker deck and tweeters.

[StereoInstaller1]

i have the premium sound deck and tweeters but no premium wiring? that's odd.

I have a 1991 318is, no fader, Head Unit is CM5908. It has rear premium speaker deck and tweeters.

OK, so right here is a perfefct example of WHY I always ask what year/model/stereo. Your wiring is '91 only, as far as I know.

You have the easiest of all E30s. You can bypass, amplify, power the rears from the deck with amp power on the front, all of the above.

Its all easy, follow the directions I already posted.

Luke

[BlueBMW]

I just completed the head unit replacement in my 88 325i vert. It had the fader on the dash and that small amp in the trunk. Someone had installed an aftermarket head unit but ran it all through the stock fader / amp. Upon its removal, I found a rats nest of wires going everywhere. After pulling the fader out and following the wires back, I discovered that I only had four wires for speakers. I repurposed those wires to run the rear speakers and ran new wire for the fronts. It came out awesome!

Basically I made a chart to remind myself of which wires were going to be used for what purpose. Then I just cut and connected the wires at the stock amp connector in the trunk.

Left Rear Speaker:
(+) Radio: Yellow/Red ===> Amp: Black/Red
(-) Radio: Yellow/Black ===> Amp: Black/Violet

Right Rear Speaker:
(+) Radio: Blue/Red ===> Amp: Black/White
(-) Radio: Blue/Black ===> Amp: Black/Brown

Here's the wiring at the stock amp connection in the trunk:



The previous owner had installed some nice MB Quart components in the front, so the system sounds fantastic now! Again thanks for all the great info in this thread!

Some more pics of my dirty interior:

[CB-M3]

your pic of the connections at the trunk will help a lot.

[StereoInstaller1]

I just completed the head unit replacement in my 88 325i vert. It had the fader on the dash and that small amp in the trunk. Someone had installed an aftermarket head unit but ran it all through the stock fader / amp. Upon its removal, I found a rats nest of wires going everywhere. After pulling the fader out and following the wires back, I discovered that I only had four wires for speakers. I repurposed those wires to run the rear speakers and ran new wire for the fronts. It came out awesome!

Basically I made a chart to remind myself of which wires were going to be used for what purpose. Then I just cut and connected the wires at the stock amp connector in the trunk.

Left Rear Speaker:
(+) Radio: Yellow/Red ===> Amp: Black/Red
(-) Radio: Yellow/Black ===> Amp: Black/Violet

Right Rear Speaker:
(+) Radio: Blue/Red ===> Amp: Black/White
(-) Radio: Blue/Black ===> Amp: Black/Brown

Here's the wiring at the stock amp connection in the trunk:



The previous owner had installed some nice MB Quart components in the front, so the system sounds fantastic now! Again thanks for all the great info in this thread!

Some more pics of my dirty interior:

Do NOT do this, you have lost 1/2 of your decks power.

Please follow my instructions: if you are using deck power to run the speakers, you need 8 wires.

[BlueBMW]

Allow me to clarify.

I completely removed the fader knob and used four of the wires between the fader and the stock amp as pos and neg for the two rear speakers. The connections at the stock amp connector were done to complete the connection to the speakers. I ran new wire to both front speakers from the head unit. I did not use any of the stock wiring of the front speakers. So in the end there are 8 wires for speakers coming off the head unit.

I was just trying to show how I repurposed the stock wiring on a 4 wire / fader in dash car that didnt have the twisted pairs further back in the harness. In the end, the fader is gone, the stock amp is gone, and new speaker wires are installed for the front speakers. Rears are wired using existing wiring.

The deck that was in the car when I bought it was wired through the fader / stock amp and was only using two channels of power. That seemed silly to me. After installing this deck and using all four channels without going through the stock fader / amp, the sound quality has gone up immensely.

Sorry about the confusion.


Here's a complete list of how everything is connected.

Deck Connections:
Car ---> Deck
Red/Green ---> Yellow (12V Const)
Violet/White ---> Red (12V ACC)
Brown/Black x2 ---> Black (Ground)
Gray/Red ---> Orange (Illumination)
White ---> Blue (Antenna On)
White ---> Blue/White (Amp On)



Speaker Connections:
L/F + R/F speakers: New Wire directly from deck to speakers

L/R:
Speaker + ---> Black/Red ---> Yellow/Red ---> Green (L/R +)
Speaker - ---> Black/Violet ---> Yellow/Black ---> Green/Black (L/R -)

R/R:
Speaker + ---> Black/White ---> Blue/Red ---> Violet (R/R +)
Speaker - ---> Black/Brown ---> Blue/Black ---> Violet/Black (R/R -)

[StereoInstaller1]

Gotcha...perfect

[CB-M3]

why did you have to run new wires for the 2 front speakers instead of using stock?

[StereoInstaller1]

why did you have to run new wires for the 2 front speakers instead of using stock?

In his case, being early premium and using deck power for all 4 corners, the logical thing to do is use new wire for the fronts.

Had he used an amp, no wires would be necessary, but since there are 4 wires to the amp, they can be "re-purposed" to be rear speaker wires.

The nice thing about this setup is being able to convert to using the stock wire and an amp if so desired.

Make sense?

Luke

[redhotchilipepper]

Could someone tell me if this will work okay in my non-premium '85 318i?

All stock wiring, as follows: (behind the dash):
A single Yellow/brown (left side ground, I believe)
A single Blue/brown (right side ground, I believe)
Yellow/red (FL +)
Blue/red (FR +)
Yellow/black (RL +)
Blue/black (RR +)
The usual power, memory, and illumination wires
Fader, which I bypassed and removed a while ago to put another switch in the dash

Alpine CDE-9845 head unit
Stock 5.25" front speakers (non-premium I guess?)
Premium "boxed" speakers on the rear deck (from junkyard)

I am about to install a Planet Audio 1800.5 amp and LukeBox with an Infinity 1062w subwoofer. I read through the 13 pages of posts and it sounds like i need to use the rear stock wires for the rear speakers, and run new wires for the fronts. HOWEVER: why can't i cut the 2 pairs of rear wires at the "halfway" point behind the back seat and then use the rear half of my split to power the rears, and the front half of my split to power the fronts (rear wires connected to front wires behind the dash)? That way I don't have to run as much new wire! Thought I'd ask you pros before attempting.

[benyen soljax]

Draw a diagram in paint, this doesn't make sense. Running new wires for the front in the non-premium cars I think is because you don't have enough ground wires with the stock wiring. So instead of using one ground per side or whatever, you use the stock grounds for the rear speakers and then wire up new stuff for the front. I could be wrong and I haven't played with the e30 wiring extensively.

The premium wiring sure does make this a whole lot easier, just snip the back and connect them together or to an amp and done.

[redhotchilipepper]

Okay I have drawn it up for you, hopefully you can see my cruddy upload:

This is what my current wiring looks like:


And this is what I would like to do, so as to run a minimal amount of wire:


There may be a better way to do this, but I definitely want a ground for each speaker. Thanks for the help.