Radio Wiring and Amp Bypass

[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.

[CB-M3]

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

[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:

[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

[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]

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]

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.

[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]

Luke, can you check over my wiring labels? PM'ed ya.

[StereoInstaller1]

so can you use the factory wires for this amp bypass with new head unit? whats the benefit of running new wire? is it going to a bigger awg wire?

how do i know if i have premium sound in my e30?

1. There is no wire on the market today that is as good as stock. Unless you are running HUGE power, use the stock stuff.

2. First, look for tweeter pods and rear speaker pods. Second, look just in front of your antenna, under the trunk liner, next to and on the same bracket as the check relay pack, that is your stock amplifier location.

Luke

[CB-M3]

so can you use the factory wires for this amp bypass with new head unit? whats the benefit of running new wire? is it going to a bigger awg wire?

how do i know if i have premium sound in my e30?

[thebonuslevel]

Yeah I was looking for more resources on my car because I am very interested in keeping it maintained and improving the very small quirks it has. I am very happy I got to keep most of the stuff stock as it is not only cheaper but looks better imho. Photos can be found in my members gallery. Again, excellent resources here and I am very happy to be part of the e30 and r3v community.

[StereoInstaller1]

Amazing, just amazing. I took my car to 2 stereo places assuming that it would be a simple deck swap as I already had the head unit. Having no tools, since I just got reassigned to a new duty station and my household items are still being shipped, I decided to take my car to a stereo installation place. I figured the 40 dollar labor would be comparable to the tools I would require and not to mention the 1h vs 1 afternoon time frame of trying to figure it out myself. The first place said that I needed new speakers new wiring and basically an entirely new sound system. The 2nd place I took it to agreed to do a hardwire but they couldn't figure out the wiring and told me that I would need to rewire the car as well. I called bullshit and found my way here.

Luke your guide, once I found it, as well as the pictures in QUICKSR20's thread about his install (here:http://www.r3vlimited.com/board/showthread.php?t=219813) made this a snap. It sounds great and I am very pleased with the outcome.

Haha...you should have shown them this thread!

I mean, seriously, where else you gonna get a 32 year veteran installer (especially one who was working on these cars when they were new) telling you step by step how to do this shit?

R3V kicks ass, don't it?

Rock on, brother, and thank you for keeping all of us free!

Luke

[thebonuslevel]

Amazing, just amazing. I took my car to 2 stereo places assuming that it would be a simple deck swap as I already had the head unit. Having no tools, since I just got reassigned to a new duty station and my household items are still being shipped, I decided to take my car to a stereo installation place. I figured the 40 dollar labor would be comparable to the tools I would require and not to mention the 1h vs 1 afternoon time frame of trying to figure it out myself. The first place said that I needed new speakers new wiring and basically an entirely new sound system. The 2nd place I took it to agreed to do a hardwire but they couldn't figure out the wiring and told me that I would need to rewire the car as well. I called bullshit and found my way here.

Luke your guide, once I found it, as well as the pictures in QUICKSR20's thread about his install (here:http://www.r3vlimited.com/board/showthread.php?t=219813) made this a snap. It sounds great and I am very pleased with the outcome.

[achtunge30]

Luke - Thank you for this thread!