Radio Wiring and Amp Bypass

[camip]

Good point on the shop I doubt they can do it. Do i have to run new speaker wires I'd rather keep the stock wires. How do I tell if I have premium sound or not?

[Gubernaculum]

Premium sound vs. non-premium also makes a difference. Worst case you run new wires to every speaker. For a car that's probably worth about a grand (that's my case, at least), it doesn't make sense to pay a shop to do this unless you REALLY can't trust yourself to do it right. And then, do you trust the shop to do it better than you would on your own car?

[camip]

I'm new to wiring and e30s do you recomend that I try this myself or take it to a shop? Btw i have a 85 325e so i think this post pretains to my car.

[StereoInstaller1]

No, I have seen it many times, actually. I think it has to do with the beer served at the BMW cafeteria.

[Gubernaculum]

Yeah I got the idea from this thread, but I never saw a detailed explanation so I figured I'd put one up for posterity and maybe help somebody (like the poster right before me who did it the hard way).

Weird thing about the wire color problem is that my 87 doesn't match the 87 electrical troubleshooting manual. I think I just have a screwy harness - everything else matches the ETM except those 2 colors.

[StereoInstaller1]

Addendum to the above: either the ETM and Luke were both wrong on the wire colors of the 12v+ versus headlight dimmer wire - or the germans who built my harness were a bit drunk that day. My "12V when the headlight is on" wire was actually red/green, and my "12v+ always on" was gray/red. Go figure.

Thus my call to always check the wire...later cars changed at some point.

And yes, your "re-purposing" is correct, I think it may be somewhere in this thread.

[Gubernaculum]

Addendum to the above: either the ETM and Luke were both wrong on the wire colors of the 12v+ versus headlight dimmer wire - or the germans who built my harness were a bit drunk that day. My "12V when the headlight is on" wire was actually red/green, and my "12v+ always on" was gray/red. Go figure.

[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.

[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.

[accident]

anyone knows if my 85 318i has an amp?

No, it does not.

[autbot318i]

anyone knows if my 85 318i has an amp?

[E30me]

Luke, great write-up :-)

[P.Kelly]

What is the deal with the grey (color coded) speaker wire at the front speakers (premium sound) as well as the blue (color coded) at the from speaker. I thought the blue twisted pair was the line levee to the amp, but it shows up again (and spliced in) at the front speakers...

[clayparkley]

I just pulled out the after market HU from PO and found that the ILL gry/red wire splits into two before it comes in to the stock harness of the radio. But the other end of gry/red wire which is not connected to the HU is left cut. Does anyone know where this suppose to go? My comp unit next to the HU does not illuminate and I'm thinking maybe that's where it belongs? But I couldn't find the other end of gry/red wire coming out from the comp unit, even though I havn't looked carefully yet.

One more question two wht wire connected into one, one is P ANT and other is AMP remote right? Harness of the Pioneer HU(Deh-5000ub) I'm trying to install has only the blue/wht wire not the solid blue. So do I leave the two wht wire connected as one and connect this to the blue/wht?

[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.