Easy way to install an aftermarket radio into your factory amplified system

[itsnevo]

I noticed a lot of posts about problems and questions on how to install an aftermarket stereo into a BMW E34 or any car that has a factory amplified stereo system and I have a very easy way that will only cost you about $16 to $20 plus shipping and take about 10 minutes at the most to install. Plus the results are you get to use the factory amp and speakers without having to modify anything.

Some people have suggested by-passing the factory amp and running all the speakers off the aftermarket head unit and the problem is that at least on my E34 I have 8 speakers that would be trying to run off of 4 channels that each only put out 20 watts RMS. You would not get anywhere near the volume running 8 speakers off of the aftermarket radio as you would running it through the factory amp. It can be done, but there is an easier and extremely quick way to just swap out the head unit without having to modify any factory wires.

Not many people seem to know about this, but there is an item called an Amp Integration Harness which turns your factory speaker wires into RCA wires that plug into the front and rear preamp outputs on the rear of the aftermarket radio. The speaker wires that are on the aftermarket radio harness won't need to be used when using the amp integration harness. This harness also has all your power, ground, and remote turn on wires, so it's a complete harness. The item specific for the E34 is the Metra 70-8591 which I purchased for only $16 plus shipping on Ebay. If you would like to see what the item looks like, just do a google search for Metra 70-8591 or look it up on Ebay. I would post a picture, but I'm not permitted to post pictures yet. The stereo I picked up has 3 sets of preamp outputs (1 front preamp, 1 rear preamp and 1 subwoofer preamp) on the rear of the stereo so you can still run an additional amp and subwoofer if you want.

The really nice part is that all you have to do is connect the wires on this harness to the ones for the aftermarket head unit, then it simply plugs in between the factory wire harness that plugs into the rear of the factory radio and the aftermarket radio. If you ever want to reinstall the factory radio, (like if you were going to sell the car and wanted to keep your aftermarket radio) all you have to do is unplug the amp integration harness from the factory wire harness and replug the factory harness into the rear of the factory radio. You don't have to modify or splice into any of the factory wires by using this amp integration harness.

I've used a similar wire harness on a VW Corrado I had and it worked great and sounded awesome. The Corrado had a premium stereo system similar to the BMW and it too had a similar common ground speaker system and the best part is it didn't require any speaker replacement or speaker rewire and I could still use the factory amp so you can really crank up the volume!

Metra makes many of these amp integration harnesses for all sorts of cars that have a factory amplifier and common ground speaker system so if you know anyone who has a similar problem, chances are that Metra makes a harness for that car. Spread the word!

[12v Electronics]

ARGH x2!!

Search and learn before you post nonsense like this. It is not correct for all cars. and definitely not correct for getting more power from the stock audio system.

[itsnevo]

According to the manufacturer, this adapter is for the following cars

1990 - 2001 3 SERIES
1997 - 2001 323
1997 - 2001 328
1990 - 2001 5 SERIES
1990 - 2001 7 SERIES
1997 - 2002 Z3
1998-2000 M Coupe
1998 M3 Coupe

I found out today that I have an early wiring design that uses many smaller plugs into the rear of the factory radio which this adapter will not work on. Obviously Metra (the company that makes the adapter) is unaware that the earlier E34's had a different radio wiring harness setup than the newer E34's. This adapter is designed for the 17 pin plug on BMW radio harnesses.

I never said that this would somehow make your factory amp produce more power than what it produced before the head unit swap. I did say that your factory amplifier will produce more power than what you would get by-passing your amp and running your speakers directly off the aftermarket head unit. It seems like the average aftermarket radio claims that it puts out 50 watts per channel. In RMS, that's only about 20 to 22 watts per channel. Spread that over more than 4 channels and each speaker will receive less power than what the stock amplifier produces. Most aftermarket radios are designed for only powering a 4 channel speaker system, not a 10 speaker premium system, that's why BMW installs amplifiers into the car right from the start. It won't some how make your amp create 3 times the power it created with a factory radio.

This adapter makes it easier for anyone who has a BMW with the 17 pin plug to just swap out their radio for an aftermarket one without having to cut and splice tons of wires and having to run new wires to all the speakers. You will only have to connect 4 wires (12v constant, 12v switched, ground and remote turn on for the amp) from the aftermarket head unit harness to the Metra adapter, and then plug the aftermarket head unit harness to the head unit, plug in the 4 RCA's into the preamp outputs, and then the Metra harness to the factory wire harness.

[12v Electronics]

Are you sure about that?

Do a search here and you will find that it is not the case.

[itsnevo]

The main reason why I posted this up is because I read some threads where people were saying that if someone wants to install an aftermarket radio into their factory amplified stereo system, they need to run all new speaker wires and by-pass the amp. That's not true, you don't have to by-pass the amp to install a new head unit.

I went though the exact same problem when I had my Corrado. It too had a common ground amplified stereo system and everywhere I went to get advice on how to properly install a new head unit into my car, places such as Best Buy, Circuit City, The Sound Advantage, Mickey Shore and a few other places all told me that I needed to run new wires to all the speakers, probably replace all the speakers, by-pass the amp and run the speakers off the radio power. I found out about the Metra harness and it took me no more than 10 minutes to install a new radio using the harness, and I was able to still use the factory amp with no problems at all.

I'm not saying that this is the only way to install a new radio, but it can be a cheaper costing and quicker way to install a new head unit.

Are you sure about that?

Do a search here and you will find that it is not the case.

I found it on another website (mobilevideoauthority.com) and a few others too. I have noticed afterwords on some other websites that they have this same harness listed for the E34 from only 1992 to 1995.

[vmwerks]

OP, I think you have it backwards.. the harness allows the use of an OEM HU and and aftermarket amp not the other way around.

[12v Electronics]

But yours didn't work. Did I miss something?

Are you sure this connector will allow you to hook up your aftermarket radio to the factory amp on a common or non-common ground car?

I will tell you that it will not.

Be careful what you post. You may mislead someone.

Metra 70-8590 is the correct one for a non-common ground system.

[itsnevo]

Try to read what I posted carefully before you comment back. I said that I didn't have the 17 pin wire harness that this adapter is made for, that is why it didn't work on my BMW. BMW used the 17 pin adapter on the 92 to 95 E34's (which had one large plug that connects to the rear of the factory head unit) and I have a 1990 E34 which has many smaller plugs that do not plug into the bullet connectors that are on the 17 pin plug. This adapter is for the 92 -95 E34's that are equipped with a factory amplifier.



This is not a harness that keeps the factory head unit and changes to an aftermarket amp. Look up the definition of an amp integration harness before saying that I am misleading people. The pictures of this harness always show the side of the connector that has all the bullet connectors showing, that is the side that connects to the factory wiring harness, not the side that goes towards the radio. The wires that come off this adapter are the wires that you connect to the aftermarket head unit wire harness (12v switched, 12v constant, ground and amp turn on/power antenna), then the RCA's that are on the adapter plug into the rear preamps on the aftermarket head unit. This is what the description is for the Metra amp integration harness from other websites.


Many Vehicles today are already equiped with factory amplifiers. When upgrading to an aftermarket radio, integration with these "premium sound" amplifiers is generally the quickest and simplest way to adapt an aftermarket radio to a factory system. Most factory amplifers are six or more channels but use a four channel input at a low signal. Metra's integration harnesses include a color coded set of four male RCAs which can be used to feed a low level signal into the factory amplified system. To obtain this low signal, line output converters could be used in conjuction with the speaker outputs of the aftermarket radio, or ground loop isolators could be used along with the pre-amp outputs of the aftermarket radio.
Description
Metra 70-8591
BMW 1990-up
Plugs into OEM Radio wiring harness


Try to read what I wrote a little more carefully before trying to attack me. And if you still have a problem with this description of what an amp integration harness is, contact the company Metra and tell them that they somehow have no idea of what they are developing and selling to the public and that they are misleading people into believing that this will help them swap out their factory head unit for and aftermarket one.



All I can say is that I've used and amp integration harness before and it's obvious that you haven't if you are trying to say that it is for connecting a factory head unit with an aftermarket amplifier.



The Metra 70-1785 amp integration harness is the exact model that I used for my VW Corrado which had the common ground premium stereo system and guess what, it worked exactly how it said it would! It turned the speaker wires into RCA's that plugged into the rear preamps on the aftermarket radios and I kept all the factory speakers and amp and just changed out the head unit to a Pioneer CD player.

[Halston Pitman]

You definitely want to start from scratch on a common ground car. We tried(just for fun) to wire a Panasonic 7413U into a factory Premium car. 1986 535i with the common ground.

The amp started clipping at ohhhhh 1/8 volume Was bad news!

[12v Electronics]

I wasn't attacking you. I was telling you that you cannot use the adaptor you specify. Try it and you will see that it will not work.

[Halston Pitman]

Now Now Guys

[12v Electronics]

This is the harness you are talking about:


I'm not sure what you would use it for.

Here is the correct one to install an aftermarket radio in a late model BMW:


I hope that clears up any confusion.

[Halston Pitman]

Top harness would be great to run amps but not great for connecting to OEM amp

[itsnevo]

The RCA cables on that top harness plug picture plug into the rear of the aftermarket radio (preamps), they do not go to RCA cables that run all the way to an aftermarket amplifier. It is plugging the amp integration harness RCA's into the head unit preamps that complete the signal for sound to travel to the factory amp. If you tried to run RCA's from the Metra harness back to an aftermarket amp, the radio would have no way to send any sound signals to the amp, so it would be just like connecting an extension cord to itself, you are cutting out the part of the system that creates the signal and no power will be transferred. Just think of it this way...on the factory harness you have the speaker wires going from the amp to the headunit. When you change the radio to aftermarket and use the Metra harness, it changes those wires into RCA's. If you tried to send the RCA's back to the amp, then you will now have no speakers hooked up to the head unit because you just sent those speaker wires back away from the radio. The whole reason this adapter was made was to simply swap out your factory radio and install an aftermarket radio without having to bypass the factory amp. I know for a fact that this harness is made for keeping your OEM amp and just changing your head unit to an aftermarket one. I've done 2 cars both with a common ground factory amplified sound system using this type of harness and in each case I changed out the factory radio and kept the OEM amp and speakers without rewiring anything.

The harness below that one is for a non amplified system where the speakers are powered directly off the head unit itself and not an OEM amplifier. By using that harness on an OEM amplified system, you would have to bypass the amp and run all new wires from the head unit to all the speakers. That again is why the amp integration harness was made.

As far as having to start from scratch on your 86 535i with the common ground system, if you had a similar radio that I had in my 90 525i where there are several smaller connectors that connect to the rear of the radio, you didn't have to do all that. There are ways of connecting an aftermarket radio to a common ground amplified speaker system without having to "start from scratch" and that is why I posted this information up. The sad thing is if you have a similar system as I do, you didn't have to buy any additional harnesses, bypass the factory amp or run any new wires at all. All you need is the aftermarket radio harness and some connectors.

And just to clarify, I do have the common ground factory amplified system found in older E34's in my car with a JVC aftermarket radio in it now working awesome and I am using the OEM amp and speakers without running new wires to any of the speakers and it took me about 7 minutes to install the JVC radio into my car.

I've installed aftermarket radios into 3 cars now that had an OEM common ground amplified system without having to bypass any amp or rewire any speakers.


Here is a diagram on how you would use the Metra amp integration harness to swap out a factory radio for an aftermarket one into a BMW with the factory 17 pin wire harness without having to bypass the factory amp and rewire any speakers. You need to connect the RCA cables to the rear and front preamp outputs on the rear of the radio because this is what makes the factory amp get the signal to produce sound. Otherwise you will only be running a remote turn on wire to the amp and that's it. These RCA's are NOT intended for an aftermarket amplifier with a factory head unit.



Here is how you replace a factory radio for an aftermarket radio with the older BMW radio harness with many smaller connectors into a common ground amplified system without having to bypass the factory amp and rewire all the speakers. I know for a fact that this works because I'm driving a 1990 E34 with a JVC HD radio in it right now and I didn't bypass any amp or replace any speaker wires.



These are only for BMW factory amplified stereo systems that are the same as the two available in the E34's. The top diagram was used on the factory amplified stereo systems found on the 92 to 95 E34's and the bottom is what was used on the common ground factory amplified systems found on the 89 to 91 E34's.

The bottom diagram was a diagram that I found on the internet. I took a meter to the two 12 volt wires to see which one was the 12v switched and which one was a continuous 12v source. Make sure you connect the two brown wires that are twisted together and have a loop connector that was mounted to the rear of the factory radio onto the aftermarket radio. Unless there is some new adapter out there that I am unaware of, you will have to cut the wires going to the 12v switched, 12v constant, ground, antenna/amp turn on and speaker wires from the connectors going to the rear of the factory radio and connect them to the corresponding wires on your aftermarket head unit harness. Seeing as this is a common ground system, on the diagram where is shows #6 through #13, there will only be 4 wires that connect to the radio and those are all your + speaker wires. On your aftermarket radio harness there will be both the + and - wires, but all you need to connect is the + wires. Tape off the - speaker wires on your aftermarket wire harness, you won't use them at all.

If anyone has a BMW with the 17 pin connector on the rear of their factory radio and they want to upgrade just their head unit while keeping their factory amp and speakers, I am selling the 17 pin Metra amp integration harness I have for $15, and I would be more than happy to help install the new head unit totally free to show the buyer how easy it is to use and show how you don't have to bypass the amp and run all new wires. I bought the Metra harness not knowing that I didn't have the newer 17 pin factory harness.

For anyone who has the older style radio wiring which has several smaller connectors that plug into the rear of the factory radio like mine was with the common ground amplified system and they want to swap out their factory radio for an aftermarket one while keeping the OEM amp and speakers, I would be more than happy to show them how easy it is to install. It took me about 7 minutes to install my JVC HD radio into my OEM common ground amplified system.

If anyone near the Rochester, Michigan area would like to see how easy it is, let me know. This doesn't have to be a huge project to tackle. This is way easier, quicker and cheaper than some people on here make it out to be.

If anyone still doubts that the Metra amp integration harness is designed to allow you to keep your factory amp and speaker wiring in a factory amplified common ground system while letting you just change out your factory head unit for an aftermarket one, I'll be using another Metra amp integration harness in another common ground factory amplified car sometime soon and I'll take pictures of the step by step process and post them up here.

[12v Electronics]

Won't work





Bad Idea

[itsnevo]

Here's a picture of the Pioneer radio I installed into my Volkswagen Corrado using the Metra 70-1785 amp integration harness into a common ground factory amplified stereo system. I installed it EXACTLY as I have in the diagram and it worked perfect.


And this is what the Metra 70-1785 harness I used looked like.



This is what you need to use on certain year VW's to change out your factory radio for an aftermarket one and still keep your common ground factory amp and speakers with out having to rewire anything or bypass the amp. I know it worked because I used the harness and I had a working radio and working factory amp.

This harness below is the one I would have had to use to hook up an aftermarket radio if I didn't have the common ground factory amplified stereo system.



I had installers at a Best Buy swearing up and down to me that there was absolutely no way to keep the factory amp and not have to rewire all the speakers when hooking up an aftermarket radio to a common ground amplified system and they wanted to charge me $130 for just the re-wiring and after a little research, $15 later for the Metra harness and a few minutes installing I had a great sounding stereo system with nothing changed other than just the head unit.

Won't work





Bad Idea

It does work..I've done it before with no problems on other cars and even other people on here have said that they had multiple BMW's that had the older system and they did the aftermarket head unit swap on each one with doing it that exact same way that I have in the lower diagram and had no problem at all. I guess they are all wrong too because they did it and it worked, but because you don't think it will work, they are wrong.

I have it in my E34 right now and guess what....IT WORKS!! Don't tell me it won't because IT IS WORKING!

How many factory amplified systems have you changed out a factory radio for an aftermarket one without bypassing the amp and rewiring the speakers?

I know that I've only done 3, but they went together with absolutely no problems at all and exactly how they are diagrammed above. Instead of just telling me that it won't work, try it like I have it diagrammed and see for yourself. You can try to tell me over and over again what your opinion is about this, but I'm the one who had successfully done it 3 times with absolutely no problem at all.

Results speak more than words.

Find someone with a BMW which uses the 17 pin harness and has the factory amplified system somewhere near Rochester, Michigan who wants to swap their factory radio for an aftermarket one without bypassing the factory amp and rewire the speakers and I'll be more than happy to prove you wrong.

I have the Metra harness, just find someone and I'll be more than happy to show them how.

[12v Electronics]

Ok- lets leave the common ground system out of this discussion for the time being. Lets talk about the E36 BMW because it uses the same connector as the one on the Metra harnesses you show.

The factory amplifiers in these cars use a balanced high level input (about 10 volts at max volume). The Preamp outputs (RCA's) on aftermarket radios are unbalanced and usually have a max voltage of about 4 volts at max volume. That is on 4v pre-out radios and is usually only on the better units. Most are around 2v.

Using the adaptor you specify takes the unbalanced 4 volt signal and runs it through the stock speaker wiring headed to the amp. If the signal makes it to the amp, it is less than half of what the amp expects and is not balanced. Along the way it has picked up an ENORMOUS amount of interference and noise. So if you get any sound out of the system, it will be very low and filled with tons of noise. I have no idea why your favorite company would manufacture something like this, but for arguments sake, I say it will not work.

The proper connector is the one I told you. You do loose the balanced connection, but it does work well.

This connector also is the same for all non-common ground E34's, E38's and most E39's and E46's.

As far as the early common ground cars, you really should not connect them to a non-comon ground radio. It eventually will fail if not immediately.

This is why I am disputing your thread. I appreciate you trying to educate people, but make sure it is good information before you do it. The proper information is all over this forum. If you would have done a bit of research, you would have saved us all some time and bandwidth.

[itsnevo]

Have you actually tried to install the Metra amp integration harness in to the E36 the way I have it in the diagram? Because so far you've said that this is only for installing an aftermarket amp with a factory radio and that the RCA's on this harness would go back to an amp and that you can't connect an aftermarket head unit to a factory amplified stereo system without having to bypass the amp, so that makes me believe that you have never tried to install one of these amp integration harnesses the way it is in the diagram. If you haven't already bypassed the amp and rewired any speakers on your E36 and are still using a factory radio, just pick up an amp integration harness and just try to install it exactly the way it is in the diagram.

I would really like to have the opportunity to try to install one in an E36 myself to see if I run into any problems but all I can say is take a few minutes to look up "amp integration harness" on the internet and see how each website describes what it does. This harness was created to make it easy to install a new head unit while keeping your stock amp and speakers without having to rewire the speakers. Also, if you tried to run the RCA's back to an amp instead of to the rear of the aftermarket radio, then you will only have the 12v constant, 12 switched, ground and antenna/remote turn on wires connected to the radio and you would only have a remote turn on wire connected to the factory amp. There would be no speakers connected to the radio and no signal going to the amp, just a amp turn on wire.

I'm not trying to start some war here with you or anyone else on this forum, but I have used this type of harness in the past and hooked it up the way it is in the diagram and it worked everytime with absolutely no problem. I had my Corrado for over 6 years with the Metra amp integration harness installed with a CD/MP3 Poineer radio and everything else stock and I never had a single problem, and in fact I still once in a while talk to the kid who bought the Corrado and he even said that he's had absolutely no problems at all with it.

As far as changing the factory radio out for an aftermarket one on the older style radio wires while keeping the factory amp and speakers, the member hey808 has had a few BMW's that he did this to and he has never had any problems. I have my E34 done this way too and again, I've had no problems.

I have a friend with a 2000 BMW 323ci with the amplified stereo system and if he has the 17 pin plug on his BMW, I'll see if he will let me temporarily swap out the factory radio for an aftermarket one with the Metra amp integration harness I have. I'll even video tape myself installing the harness and radio to show you.

You said that you have the E36 right? Would you happen to know if the front seats in your E36 are interchangeable with E34's? I've seen seats from E36's for sale alot on the internet and I'd like to swap out my seats for some heated ones.

[bboyvek]

the more i read this thread that more confuse i get, to begin with anyone can swap headunit on a bmw, not need to by pass amp or re wire speakers, lol,

[12v Electronics]

Your 95 325i will only require the adaptor I specified. No rewiring necessary.

Very simple. Do not use the one he specified. It will not work on your car. If you have a VW Corrado, it may.

[bboyvek]

lol, but i dont like to use wire harnesses either way,,i think they are a waste of money

[12v Electronics]

Maybe a waste of money for you, but a pleasure for the next owner

[Compgeek256]

You said that you have the E36 right? Would you happen to know if the front seats in your E36 are interchangeable with E34's? I've seen seats from E36's for sale alot on the internet and I'd like to swap out my seats for some heated ones.

A little OT, but e36 seats will not work in an e34 unless you make some custom brackets. You'd be better of buying some heated e34 seats.

[bboyvek]

"Maybe a waste of money for you, but a pleasure for the next owner "

If u planning on selling ur car, for god sake use an adaptor, correct. On the other hand, if u wont sell her, do what u wish or feel comfortable with...

[clutch328is]

I have a '97 328is. I am still shopping for my aftermarket radio. I have already purchased the 70-8590, but think the 70-8591 is REALLY what I wanted. It seems odd that Metra is selling an item like this that simply doesn't work?

12v, can I get a clarification? The picture you posted of the 70-8591 say it is designed for my year make and model, but you say it will NOT work? Or were you just saying it wouldn't work for the e34? I got lost in the back in forth.

*EDIT: My goal is to install an aftermarket Head Unit with ipod connectivity and use the existing BMW amp and speakers and keep it clean, so I can reinstall the OEM radio if/when the car is sold. Amp harness appears to be cleaner and less mess than the 70-8590