Radio Wiring and Amp Bypass

[StereoInstaller1]

YES!

Holy crap, yes, that is exactly how it is done.

Do that connection behind the back seat and "re-purpose" just like your diagram shows.

If you get stuck, hit me up...but I think you got it.

Luke

[StereoInstaller1]

and yes I know, there are more tutorials needed...

[redhotchilipepper]

Got it, thanks.
I will do the install tomorrow morning!

[CB-M3]

Got it, thanks.
I will do the install tomorrow morning!

can you take pics of the cut and connect at the rear seat?

[StereoInstaller1]

can you take pics of the cut and connect at the rear seat?

The pics you are looking for are in this thread....good luck, I created a monster!

[CB-M3]

I took out the amp today and looked at the wires in the trunk. Got all the wires identified for between amp and speakers but still not sure on a few wires to head unit. See pic. Basically I'm going to connect all the RF+ to RF+ and LF+ to LF+ and so on. I'll see what's left after I do that.

1) I have 4 wires (2 yellow/brown and 2 blue/brown) that join up to 1 Brown/Black wire. These are the Left and Right channel ground at AMP end only. What do I do with these? Is this what people mean by common ground? Leaving the booster amp to speakers I would need to provide ground via the (2 yellow/brown and 2 blue/brown) from head unit? For instance there are 2 yellow/brown for Left Channel Ground but how do I know which one is Left Front and Left Rear?

2) What do I do for the 12V wires?

3) Do I need the solid Brown Wire (ground)? Connect it to the 4 to 1 Brown/Black wire?




BETWEEN HEAD UNIT AND BOOSTER AMP

Yellow/Red - Left Front Channel
Yellow/Black - Left Rear Channel
Blue/Red - Right Front Channel
Blue/Black - Right Rear Channel
Yellow/Brown - Left Channel Ground at Amp End Only
Blue/Brown - Right Channel Ground at Amp End Only
Brown - All Channel Ground at Head End Only
(note that the all of the grounds are spliced together within the wiring harness - the system uses a common ground between the head and the amplifer)
White - 12V Switched (to turn amplifier ON when head unit ON, also runs to power antenna)

BETWEEN AMP AND SPEAKERS

Pair: Black/White and Black/Brown - Right Rear Speakers
Pair: Grey/White and Grey/Brown - Right Front Speakers
Pair: Black/Red and Black/Purple - Left Rear Speakers
Pair: Grey/Red and Grey Purple - Left Front Speakers
(note that the wires highlighted in red above all run to the crossover side of the midrange drivers, you'll want to know this to keep all your speakers in phase - make sure all of your speaker (+)s go to these wires)
(also note that the speaker circuits DO NOT use a common ground when they leave the booster amp)

[JonnyOg]

So would my system sound better without the factory amp? I'm just using the pioneer head unit you recommended.
Premium sound 91 318is

[CB-M3]

^ You are in the same boat as me. I have 318is with premium. Did you install your pioneer unit yet?

[Ken o]

Great thread! This really helped me and my son install his system.

Two questions. Everything is working but the power ant and power from the Red/Green in the dash. We are using a different power source for now. I am getting power for the ant from the Alpine unit. We had an OEM radio that was working off the OEM wire and the ant worked.

1986 325es, 10/86 build date, Premium sound, rears on BMW wire, fronts on new wire, Alpine unit.

[JonnyOg]

^ You are in the same boat as me. I have 318is with premium. Did you install your pioneer unit yet?

Yea I have the head unit it, I didnt notice any difference in sound from the old one. I'm pretty much audio retarded but I guess thats because the factory amp is what is powering the speakers and not the deck?

[Ken o]

Great thread! This really helped me and my son install his system.

Two questions. Everything is working but the power ant and power from the Red/Green in the dash. We are using a different power source for now. I am getting power for the ant from the Alpine unit. We had an OEM radio that was working off the OEM wire and the ant worked.

1986 325es, 10/86 build date, Premium sound, rears on BMW wire, fronts on new wire, Alpine unit.

Fix the antenna issue, blown fuse but very hard to tell it was blown.

Here is the odd part. The red/green seem to be the dimmer. It has no power on it until the lights are turn on and then it has 12v. The grey/red has 12v on all the time. Is this right?

[StereoInstaller1]

Fix the antenna issue, blown fuse but very hard to tell it was blown.

Here is the odd part. The red/green seem to be the dimmer. It has no power on it until the lights are turn on and then it has 12v. The grey/red has 12v on all the time. Is this right?

Yeah, they change year to year. There is a mention in this thread somewhere, I think. Too much data, I need to consolidate this mess sometime!

Oh, and your fuse issue is exactly why I tell people to use a test light (NOT a DMM or DVM) to test fuses. It is very simple to know if that fuse is good and you get to know if the circuit is live, all from a $5 test light.

Good to hear you got it up and running!

Yea I have the head unit it, I didnt notice any difference in sound from the old one. I'm pretty much audio retarded but I guess thats because the factory amp is what is powering the speakers and not the deck?

Guys, if you do the bypass, you will notice better clarity and a tiny bit more loud. Worth it IMO, I am sure you are gonna wanna do something else. It is so frustrating to me that I can't have everyone hear the $500 stereo...what you have now kinda sucks, right? Kinda thin, kinda boring....the $500 stereo sounds so amazing with the same speakers!

Luke

[CB-M3]

I found the 4 ground wires at the trunk amp where it goes 4 to 1 after pulling back on the tape. Blue/Brown is right speakers and Yellow/Brown is Front but I'm not sure how to tell which is front or rear. There are 4 wires 2 Blue/Brown and 2 Yellow/Brown that go to 1 Brown/Black wire at the amp. Probably could check with multimeter but probe leads won't be long enough to check connections at trunk and head unit.

[StereoInstaller1]

I found the 4 ground wires at the trunk amp where it goes 4 to 1 after pulling back on the tape. Blue/Brown is right speakers and Yellow/Brown is Front but I'm not sure how to tell which is front or rear. There are 4 wires 2 Blue/Brown and 2 Yellow/Brown that go to 1 Brown/Black wire at the amp. Probably could check with multimeter but probe leads won't be long enough to check connections at trunk and head unit.

Yellow/red and blue/red are the front positives, yellow/black and blue/black are the rear positives

[CB-M3]

Yellow/red and blue/red are the front positives, yellow/black and blue/black are the rear positives

I have all the positives identified. It's the ground wires that I am not clear on.