Head unit wiring with common ground

[JGood]

I have an 89 535i, and would like to wire in an aftermarket head unit. From what I understand, pre-93 e34's still used common ground, but I've read that the grounds all junction only a few inches in the harness from the factory head unit. Is this true? I'd like to know before tearing the dash apart.

If so, is it 4 channels at that point, then the factory amp splits it into 10 channels? So I can extend the 4 grounds and wire up the head unit as normal, and still have all 10 speakers functioning as normal with no ill effects?

[StereoInstaller1]

Easier than that, actually. You can simply integrate your stock amp, no extra wiring needed. It will sound OK. but not great.

Better sound on your early car can be had by bypassing your stock amp and feeding the decks speaker output to the stock 10 channel crossover, either with or without an amp in between.

In fact, one of our E34 10" boxes and a $50 woofer on a $50 amp, an aftermarket deck and the stock speakers and crossover make for one hell of a nice sound.

Way better than you would expect for a couple hundred bucks, thats for sure.

It is a shame that the later speakers won't work right with the earlier crossover, they are a HUGE upgrade...if you heard my E34, you would be stunned.

Of course, we are offering a few more goodies too...if you changed to late model speakers, used a 5 channel amp and our bitchin' new passive crossover network with our sub box and amp rack, you can have absolutely world class sound AND looks for about $1200, total. That is the exact kit I listen to personally, it is awesome.

Watch for a new thread, this new crossover is bad ass. It can be built to work with prety much any BMW newer than the E31 too, so if you change cars later, you can change the crossover as needed. This thing will change the face of how BMW audio is dealt with, it is truly a new way of dealing with an old problem.

Luke

[JGood]

I'm not really interested in spending any money in making it sound better. Only reason I want to put a head unit in is because the factory tape deck is broken, so the only option I have is the radio, can't even use a cassette iphone adapter. And I already have a nice Pioneer deck with iPhone Pandora controls sitting on my shelf, so if I can wire that in, it will cost me nothing.

Anyway, I don't understand what you mean by "you can simply integrate your stock amp". I have no idea how the audio system is wired in this car. The only thing I know is my aftermarket head unit has a total of 4 pairs of wires for speaker outputs. I just need to know how to connect that to my factory head unit wiring. From what I understand, there is not 4 pairs of wires connected to the factory head unit, just 4 + wires, then a single ground that gets used for all of the channels? But I read that the single ground gets split a few inches from the head unit connector, and divided into 4 separate wires to go into the amp, meaning I should just be able to open that junction and extend each of those ground wires to hook up all 4 pairs to my new head unit?

[StereoInstaller1]

Easier than that!

Simply connect all 4 speaker positives to the yellow/red, blue/red, yellow/black and blue/black wires, connect the decks power wires and remote wire, then ground the brown/black wires to the same brown wire as the decks ground.

Do not connect the ground wires from the deck (gray, white, green and gray, all 4 with black stripes) to anything, simply leave them disconnected and make sure they cannot short out.

Basic tunes, done.

Luke

[JGood]

Easier than that!

Simply connect all 4 speaker positives to the yellow/red, blue/red, yellow/black and blue/black wires, connect the decks power wires and remote wire, then ground the brown/black wires to the same brown wire as the decks ground.

Do not connect the ground wires from the deck (gray, white, green and gray, all 4 with black stripes) to anything, simply leave them disconnected and make sure they cannot short out.

Basic tunes, done.

Luke

Whaaaat?! Damn, that is easy.

So on the factory harness, I'll have the 4 speaker positive wires, 1 speaker ground wire, main power, main ground, and remote, and that's it? 8 wires? Is the main power a constant or switched 12v? Or does it have both?

Do you happen to know the colors of those other wires?

Thanks for all of your help Luke!

[StereoInstaller1]

I could dig them up, but just hit the ETM for switched and constant.

If you think of the wires between the deck and amp as "input wires" instead of "speaker wires" it might help ease your mind.

Luke

[JGood]

Unfortunately the ETM wasn't clear on colors of the power wires for some reason, only the 4 speaker outputs. But, I just found a diagram that someone made which looks like it should be accurate.

I did see in the ETM that the antenna is the rear window defroster. Interesting. That would explain why on my X5, the radio would get additional static when I turned on the defroster...

[JGood]

Finally got it wired up. Was having some trouble because I mixed up the amp power wire with some other wire, and wasn't powering up the amp.

It sounds great, way better then the factory radio. Fade and balance even works. I'm a happy camper!

Thanks Luke!