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Aftermarket radio to factory amp wiring help

Volvo 850 Made from 1993 to 1997, this Volvo line was available in both a wagon and a sedan, both with were graced with several trim levels.

Aftermarket radio to factory amp wiring help

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  #1  
Old 01-10-2014, 03:37 PM
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Default Aftermarket radio to factory amp wiring help

Hi again,

So - working on another upgrade project and need a little help. I want to add an aftermarket head unit in my 850 and use the factory amp. I have the SC815 combo CD/Tape unit. My car has the factory amp that I want to continue to use. I purchased this:

Amazon.com: Volvo (850, S40, S60, S70, S80, S90, C70, V40, V70, XC70, XC90)Factory Amp Interface Wire Harness Cable Plug: Car Electronics Amazon.com: Volvo (850, S40, S60, S70, S80, S90, C70, V40, V70, XC70, XC90)Factory Amp Interface Wire Harness Cable Plug: Car Electronics


It appears to have no instructions. I have made a request and have not gotten a response. It was only yesterday, and I am being impatient and thought I would ask for some help here.

There are better photos of what I have.
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I suspect I do not need the one with the grey plug at all. I think this is all speaker wiring. And since I am using the amp in the car this will not be used. I think the green plug breaks down this way.
Black = ground
blue = antenna
red = turn on/ignition
yellow = constant 12V


Next is the part that connects to the amp - and where I have questions.
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The front L+R and rear L+R are pretty straight forward. The white wire has 4 conductors but on 2 are labeled:
An on outer jacket labeled - "shield"
black wire labeled - "ground"
Red wire - no label
White & green wire that are labeled together.

I get the ground and can find some place to find a ground connection. What should I do with the shield and the red wire.

I am hoping someone has some experience with this part. Thanks in advance for all your help.
 

Last edited by emerlin; 01-11-2014 at 08:40 AM.
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  #2  
Old 01-10-2014, 03:56 PM
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I just did this not too long ago. You should have also gotten some vampire clamps like this:


Clamp the thin red wire from the amp to the main red power wire on the harness. Same with the thin black wire, clamp it to the main ground wire on the harness.

As for the two harnesses, if I remember correctly, I did use them both. I had a friend helping me out and he handled that part of the head unit install. Good luck.

ETA: And for the shield wires, just make sure they're isolated and not touching anything. You might want to wrap the ends in electrical tape. I didn't make sure they were well isolated and I get some high pitched whining.
 

Last edited by SolamenteDave; 01-10-2014 at 03:58 PM. Reason: Shield wire discussion.
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  #3  
Old 01-11-2014, 04:01 AM
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"I suspect I do not need the one with the grey plug at all. I think this is all speaker wiring."
And how would the audio signal get to the amp Think for a second. New "head" unit is what pulls in the radio signals or plays a CD or plays an MP3. You have the "sound" coming out of the head and so you have to have the connector with the eight wires for that sound to get to the amp. They are the four speakers.
The other connector is the power for the head and and signal to the amp to turn on and or antenna to raise lower. You have a black that needs to go to a GREAT ground.
The blue should be for the antenna and or signal to the amp for on off. It might be used for both.
The red is only hot with the key on. Make sure it's fused. It should take power from the fuse under the dash but depending on the head you are using if it calls for a smaller fuse either put a smaller one in line or replace the one under the hood. It is the power for the head to operate. If you go smaller make sure the under hood fuse isn't shared by the amp or anything else on the circuit. If there's other things using power go with the inline so the head is protected at the lowest amperage it calls for.
The yellow is hot all the time as it powers the head's memory and the clock if so equipped. Doesn't need a fuse as it draws minimal amperage.
The round connector with the quadruple RCA outputs is to connect to an amp like a powered bass box or just an external added amp. The little wires ?? I'm guessing the red is to turn on the amp. Remember, turn on is totally different from power.

That was the easy part. The speakers I'm not positive on the color, if it's correct, you need to test to find out. Also if you have good ears you need to pay attention to "+" and "-". Other wise you will have a system that's out of phase and to some people it's not only noticeable but painful from a stereophonic standpoint. The head will put out plus and minus just like the battery and so will everything up to and including the speakers. You need to keep all the positives wired together and all the negatives wired together. It's not hard you just have to pay attention.
If I've been to basic, sorry but rather beat you up with little stuff than have you turn some speaker wire into a light bulb filament

I'm old school and always try to stay away from the "vampire" scotch locks. Solder and shrink wrap. Second best, butt connectors. Vampire only if you have to or if you are actually adding a second lead. Only reason to use them is if you wanted to tack on your connectors and leave the factory ones there to put the original head back in for resale.

I'd recommend a filter in the power supply line (red wire). It keeps the alternator from introducing a whine into your system.
.
.
 
Attached Thumbnails Aftermarket radio to factory amp wiring help-amp_wiring_diagram_lg.jpg   Aftermarket radio to factory amp wiring help-850-radio-wiring-connectors.gif   Aftermarket radio to factory amp wiring help-stereo-power-noise-filter.jpg  

Last edited by Kiss4aFrog; 01-11-2014 at 04:07 AM.
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  #4  
Old 01-11-2014, 09:05 AM
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Thanks Kiss for the help. I should have been more clear in my first post.

FYI - I agree with you on the vampire connectors. I like crimp/bell caps in most instances for a solid wire to wire connection. YMMV

I was indeed correct, the grey harness is for speakers and in an installation with a factory amp is not needed. My factory radio had nothing connected to that connector. I do not have a picture of the back of the radio, but you will see two connections one for power, turn on, antenna, etc... and the other is for the speaker outs. In fact the I have pictured above is not the correct green harness either.... I will take some photos before put this back together if I get it working.

If I were to bypass the factory amp, I would use the other connector to provide power to the speakers. I would have to find the amp behind the dash with is simple and get into the harness for the direct speaker connections. I really want to keep the factory amp, I feel it is likely better that the 4x40 power the new head unit supplies.


The green adapter above is for an S80 which apparently has the same amp interface as the 850. I have found the thread where people have made there own amp cable and is seems to be correct. So....

My factory harness had the following - no surprises here.
Black = ground
Red = ignition
Yellow = constant 12
Orange = illumination
Blue = antenna (FYI - I also did the antenna switch mod. Now was a simple time to add it, and it works great)
Blue white = amp turn on

Now on to the aftermarket white cord...
- I currently have the RCAs connected to the preouts on the headunit
- the black wire connected to the ground on the harness
- the red is connected to the ignition red on the harness
- the green and white were taped together from the provider so left those alone.
- the braided shield is simply cut off in the cable and left.

So hooked up in this configuration above everything works, but I am getting a significant amount of noise. What i have done so far:
1. I have stripped back the white wire to reveal more of the braided shield. I think extended that and connected to the grounding screw on the factory radio. This eliminated part of the noise problem but not all.
2. I am wondering if the red conductor in the white wire is really an amp turn on lead. If this was similar to an aftermarket amp, you would provide power to the amp AND a separate turn on. I will work on this and report back.

So much for this being easy...
 
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Old 01-11-2014, 10:32 AM
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So yes - I recommend using the blue strip to the aftermarket red wire. This turns that amp on when needed as opposed to the red wire (ignition power) being on all the time.

Here are my current issues -
1. I have a lot of noise (car not running - just key in on position). As soon as I unplug the antenna the noise goes away. I must have ground issue somewhere.

2. not sure if this car has a subwoofer as part of the factory radio, but what music have listened to seems to have little or now bass. I have not done anything with the radio so that could be it.

I will keep plugging away and report back.
 
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Old 01-11-2014, 03:36 PM
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On my system I ran the components to their own body grounds instead of using the "black" wire ground supplied in the harness.

With the noise you have you might still want to add a suppressor to the power feed.

No sub woofer in the system I've ever run across in threads or wiring diagrams. Very likely the original speakers are shot. Especially the fronts. It's a common cause of mysterious dash rattling and it turns out to be the speaker magnet has fallen off and is rattling around in the dash.

If you're upping the power it's very likely you'll want to replace all the speakers too. After close to 20 years they're due for retirement.
 
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Old 02-15-2014, 04:08 PM
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Hello There, I purchased the same harness from a different seller. this is what they sent me.
the grey harness is only for the SC units, you wont need it if you have an HU unit.

hope this helps.
 
Attached Thumbnails Aftermarket radio to factory amp wiring help-wiring-guide.jpg  

Last edited by 850R4Ever; 02-15-2014 at 04:11 PM.
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  #8  
Old 08-04-2014, 03:44 PM
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Just wanted to let you know that this really helped me. I was at my wits end. Thanks! - JR

Originally Posted by 850R4Ever View Post
Hello There, I purchased the same harness from a different seller. this is what they sent me.
the grey harness is only for the SC units, you wont need it if you have an HU unit.

hope this helps.
 
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Old 08-15-2014, 10:54 PM
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u r welcome JR
 
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Old 09-12-2014, 12:18 AM
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Originally Posted by emerlin View Post
I will keep plugging away and report back.
Did you ever have any luck with the noise? I have the same kit and am having the exact same problem as soon as I put the key in.
 
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  #11  
Old 07-18-2016, 08:23 PM
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Regarding

"My factory harness had the following - no surprises here.
Black = ground
Red = ignition
Yellow = constant 12
Orange = illumination
Blue = antenna (FYI - I also did the antenna switch mod. Now was a simple time to add it, and it works great)
Blue white = amp turn on "

For blue wire, what this antenna is for? radio? i think there is antenna wire input port on the back of oem. thanks.
 
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