# Aftermarket stereo wiring help! aarrgh! UPDATE



## sweatystt (Jan 29, 2015)

So im trying to connect up my Alpine aftermarket head unit. I've got the pc9-410 pc5-90 harness adaptor but still nothing. I seem to only have 2 plugs coming out of the car but 3 on the harness?! I've just removed my mums aftermarket unit but she had 3 plugs coming out of the dash. And also an additional live which split to the new harness. Any help much appreciated or even better a link/diagram. Cheers


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## paulw12 (Mar 31, 2015)

I think pc9-410 harness is only for cars with BOSE, have you got bose written on front door speakers?
All the plugs only fit in one place, so you can't go wrong really.


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## sweatystt (Jan 29, 2015)

paulw12 said:


> I think pc9-410 harness is only for cars with BOSE, have you got bose written on front door speakers?
> All the plugs only fit in one place, so you can't go wrong really.


Yeh got bose mate. Plugged in both plugs but nothing. Even tried swapping a couple of the pins in the red connector as seen in a old post but still nothing.


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## paulw12 (Mar 31, 2015)

ok, good, you seem to have the correct harness.
If you swap the red and yellow bullet connectors, you should be able to power it up.
I had to run another switched live feed, as the car only has a permanent live to keep it memory & clock going.
Have you connected the blue wire from headunit,so that the Bose amp gets switched on, and FM aerial booster gets power from headunit.


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## sweatystt (Jan 29, 2015)

paulw12 said:


> ok, good, you seem to have the correct harness.
> If you swap the red and yellow bullet connectors, you should be able to power it up.
> I had to run another switched live feed, as the car only has a permanent live to keep it memory & clock going.
> Have you connected the blue wire from headunit,so that the Bose amp gets switched on, and FM aerial booster gets power from headunit.


No mate not swapped any connectors. I have a blue and white wire coming out of the stereo (not connected) but the blue goes into a black plug. Why do I have only 2 plugs in the car but 3 off the harness?


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## paulw12 (Mar 31, 2015)

Yeah the blue & white wire from headunit, labelled antenna or something, is what provides the signal for bose + fm.
Read matts write up
viewtopic.php?f=2&t=983937
If you temporarily swap red/yellow bullits around the headunit should at least power up for a test.


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## paulw12 (Mar 31, 2015)

I forget about the harness connections.
My headunit used the front phono pre-outs for the speakers, has your headunit got phono pre-outs?
I think the harness connector that doesn't fit anywhere might be for speaker signals, and we don't need it, as the pre-outs are being used instead.

edit -more reading in knowledge base
viewtopic.php?f=2&t=160192


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## sweatystt (Jan 29, 2015)

paulw12 said:


> I forget about the harness connections.
> My headunit used the front phono pre-outs for the speakers, has your headunit got phono pre-outs?
> I think the harness connector that doesn't fit anywhere might be for speaker signals, and we don't need it, as the pre-outs are being used instead.
> 
> ...


Cheers yeh got phono pre outs? Tried swapping yellow and red....nothing.


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## paulw12 (Mar 31, 2015)

Might be worth plugging OEM headunit back in to check that it powers up, you might have blown a fuse?
Oh and make sure you get cds out of changer as it won't power up without OEM headunit in.

Iam sure I swapped the red & yellow bullits around, and one combination let the headunit power up.
Have you run a switched live? this will stop your battery draining as well.


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## sweatystt (Jan 29, 2015)

paulw12 said:


> Might be worth plugging OEM headunit back in to check that it powers up, you might have blown a fuse?
> Oh and make sure you get cds out of changer as it won't power up without OEM headunit in.
> 
> Iam sure I swapped the red & yellow bullits around, and one combination let the headunit power up.
> Have you run a switched live? this will stop your battery draining as well.


I would but its now in my mums roadster miles away! Will check fuses. Not done switched live yet. Will try that later. All cd's out ta. What about the phono pre outs how are they used?


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## paulw12 (Mar 31, 2015)

They just take front left & front right speaker signals to the bose amp which does the rest.

Basically you need to get power to both red and yellow inputs to the headunit for it to power up. If then when you switch it off it loses its memory & clock settings, you need to swap the red & yellow wires around, that's why they have bullet connectors to make it easy.

later on when you get it working, there might be a setting in the Alpine that turns its internal amp off, as the pre-outs won't need it. There was on my kenwood , supposed to make it sound better 8)


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## sweatystt (Jan 29, 2015)

paulw12 said:


> They just take front left & front right speaker signals to the bose amp which does the rest.
> 
> Basically you need to get power to both red and yellow inputs to the headunit for it to power up. If then when you switch it off it loses its memory & clock settings, you need to swap the red & yellow wires around, that's why they have bullet connectors to make it easy.
> 
> later on when you get it working, there might be a setting in the Alpine that turns its internal amp off, as the pre-outs won't need it. There was on my kenwood , supposed to make it sound better 8)


So do I need to connect those up? If so to what and how?  Can I run a live off the battery? :?


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## paulw12 (Mar 31, 2015)

Read those links I posted.
There is a switched buss bar in drivers footwell, you'll need an inline 10amp fuse. Then when you switch ignition off the radio will switch off as well.
I fitted this GLI as well
http://www.ebay.co.uk/itm/20-AMP-RCA-No ... 3ca60c87e6
supposed to prevent any hum, no idea if I needed it or not :lol:


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## sweatystt (Jan 29, 2015)

paulw12 said:


> Read those links I posted.
> There is a switched buss bar in drivers footwell, you'll need an inline 10amp fuse. Then when you switch ignition off the radio will switch off as well.
> I fitted this GLI as well
> http://www.ebay.co.uk/itm/20-AMP-RCA-No ... 3ca60c87e6
> supposed to prevent any hum, no idea if I needed it or not :lol:


Ok thanks mate. Sorry whereabouts in the footwell? Behind the fuse box?


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## paulw12 (Mar 31, 2015)

Yeah its kind of behind the fuse box, but you have to take trim off under steering wheel, and lay in the footwell and look up a bit. There are good photos in the links.


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## sweatystt (Jan 29, 2015)

paulw12 said:


> Yeah its kind of behind the fuse box, but you have to take trim off under steering wheel, and lay in the footwell and look up a bit. There are good photos in the links.


Ok so ive ran a switched live off the buss bar but still nothing. Tried the yellow red swap thing still knowt. Cant even get the bloody thing to power up.


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## asahartz (May 24, 2014)

So by this point you need to be checking things with a multimeter.

Yes, there are three plugs on the original harness but the red one is not required - it only has a few wires in it anyway and they are all for features which don't exist in aftermarket units.

Take a multimeter, earth the negative probe and check for 12v on the red wire, and then on the yellow wire. Check that the black wire reads 0 resistance to earth. If you have all these, then the HU should power up unless it is faulty. If not, you've found your problem.


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## infidel.uk (Feb 21, 2015)

sweatystt said:


> paulw12 said:
> 
> 
> > Cant even get the bloody thing to power up.


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## sweatystt (Jan 29, 2015)

asahartz said:


> So by this point you need to be checking things with a multimeter.
> 
> Yes, there are three plugs on the original harness but the red one is not required - it only has a few wires in it anyway and they are all for features which don't exist in aftermarket units.
> 
> Take a multimeter, earth the negative probe and check for 12v on the red wire, and then on the yellow wire. Check that the black wire reads 0 resistance to earth. If you have all these, then the HU should power up unless it is faulty. If not, you've found your problem.


Hi ive got 2 blocks coming out the dash but 3 off the harness. One of which is red which seems to be the only one that fits properly into one of the existing blocks. Obviously the blocks are slightly different with the red one being longer. The stereo was shown to be working as did the original oem stereo.


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## sweatystt (Jan 29, 2015)

infidel.uk said:


> sweatystt said:
> 
> 
> > paulw12 said:
> ...


Cheers very helpful!! :roll: :lol:


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## infidel.uk (Feb 21, 2015)

Not much more to add, im just surprised this is being so difficult. :?


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## paulw12 (Mar 31, 2015)

You are of course using the original Alpine wiring harness plugged into it as well?
Can't think of why its not powering up....


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## sweatystt (Jan 29, 2015)

paulw12 said:


> You are of course using the original Alpine wiring harness plugged into it as well?
> Can't think of why its not powering up....


Yeh mate. The fact that ive only got 2 blocks on the original wiring(coming out of the dash) doesn't seem right. The red block on my harness seems to plug into that fine but the other remaining one pugs in but doesn't seem tight. Then obviously ive got 1 left over off the harness. The slightly thicker yellow which comes out the stereo had a bullet connector in but then goes straight into the back of a block. The red I have coming out of the stereo(which doesn't go into a block is very thin. I may post a pic later showing what ive got.


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## paulw12 (Mar 31, 2015)

I remember the plugs being a bit tricky, and I initially I was convinced they were wrong, but if you discount any without any wires in, and then play around with the rest, eventually the "coin will drop" and they will clip together nicely.

edit -After that you need to do the power + earth checks mentioned above.
Its not unheard of for the bought harness to be faulty from ebay.


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## asahartz (May 24, 2014)

Any possibility of posting pics? Then we can see what you're talking about instead of trying to visualise it.


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## DazWaite (Dec 4, 2012)

Hi dude.....

If you get stuck you can always come a cruise to me and I'll sort it !!!

Or if you can wait I'm about in the midlands this weekend(near Tamworth)

Daz


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## sweatystt (Jan 29, 2015)

DazWaite said:


> Hi dude.....
> 
> If you get stuck you can always come a cruise to me and I'll sort it !!!
> 
> ...


Thanks Daz appreciate the offer may hold you to that. Think that may be next asahartz mate. I've now got the thing to power up and I have sound but it sounds shit when you turn it up!? I can hear a click noise fro the rear when i connect i think the blue to live so i assume thats my amp live? Also cant seem to get the aerial adaptor/booster to plug in. One end will one wont.


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## paulw12 (Mar 31, 2015)

At last........it powers up  what was the solution?

Have you joined all 3 blue /white wires together, 1 from headunit, 1 from FM booster, 1 from harness (to bose amp) ?
Again I didn't have any probs pushing FM booster together...


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## sweatystt (Jan 29, 2015)

paulw12 said:


> At last........it powers up  what was the solution?
> 
> Have you joined all 3 blue /white wires together, 1 from headunit, 1 from FM booster, 1 from harness (to bose amp) ?
> Again I didn't have any probs pushing FM booster together...


Pass! I just kept trying different ways. Yeh think so......here's a pic. Still not right as it sounds crap and its not storing stations.


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## mamwr (Mar 29, 2015)

sweatystt said:


> DazWaite said:
> 
> 
> > Hi dude.....
> ...


I needed to buy an adaptor for the areal. DIN to ISO or something like that. You can get them from halfords for about 3 quid. Just look at each side of the connection you need and buy the right thing.

On the adaptor you definitely need to change over the red and yellow wires. If you get them wrong it will not keep its memory.

Make sure all the blue wires are getting power.

The adaptor should take your stereo outputs and turn them into phono sockets. Then you need to put in a ground loop isolator before connecting to the phono plugs on the car side. Your adaptor should have 2x red and 2x white (or black) connectors. Make sure you are using the front ones.

I am pretty sure you will only use 2 of the 3 plugs on your adaptor.


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## sweatystt (Jan 29, 2015)

mamwr said:


> sweatystt said:
> 
> 
> > DazWaite said:
> ...


 Cheers I've got phono coming out of the stereo but nowhere else?


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## paulw12 (Mar 31, 2015)

Can't see the phono outputs from headunit in your photo, but you only need use the fronts.

I didn't wire the new red switched live to the blue wires, like you have. I used that loose blue/white wire from headunit to feed the blue wires. What you have done will send power to the amp all the time car is on , even if headunit is off, whereas the blue/white wire is switched on from headunit itself so amp is only on when headunit is on.

Also are you not feeding new red live back into headunit thro the connected blue wire?...not good

I take it this is used headunit & that's why there are no labels on the wires to help you.. 

That yellow wire you have connected to red, might want to change to, yellow to yellow, to keep settings.


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## sweatystt (Jan 29, 2015)

paulw12 said:


> Can't see the phono outputs from headunit in your photo, but you only need use the fronts.
> 
> I didn't wire the new red switched live to the blue wires, like you have. I used that loose blue/white wire from headunit to feed the blue wires. What you have done will send power to the amp all the time car is on , even if headunit is off, whereas the blue/white wire is switched on from headunit itself so amp is only on when headunit is on.
> 
> ...


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## paulw12 (Mar 31, 2015)

pc9-410 has 4 phonos on end of red plugged lead like this:-
http://www.ebay.co.uk/itm/PC9-410-AUDI- ... 58ab94c3ed
These would then plug into the 2 phonos white & red on black lead in your photo, maybe someone else can back me up here...
I don't think your harness is a pc9-410??


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## sweatystt (Jan 29, 2015)

paulw12 said:


> pc9-410 has 4 phonos on end of red plugged lead like this:-
> http://www.ebay.co.uk/itm/PC9-410-AUDI- ... 58ab94c3ed
> These would then plug into the 2 phonos white & red on black lead in your photo, maybe someone else can back me up here...
> I don't think your harness is a pc9-410??


I bought it off Ian_w off here. He advertised it as that. Bought it for his car but not used? Ive now connected yellow back to yellow and all the blue/blue whites are all together. Im left with the red which needs power but from where? It cant loop back. You can just see it at the bottom of the pic. Comes out the black plug. Also if I had phonos which plug into the back of the stereo where the hell does the other end plug? I don't have enough plugs as it is?


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## paulw12 (Mar 31, 2015)

Maybe he didn't have bose? you need to ask him.
A lot easier buying new stuff....
I recon you have non-bose harness, I suggest you buy pc9-410 from my link
The red input to headunit is taking live straight from your new live feed I assume, which is correct.

Those group of 4 phonos on headunit look like speaker pre-outputs front rear left right? if so that's where the pc-410 phonos connect.

iv'e got to go now, won't be back till Friday, good luck sorry buddy...


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## sweatystt (Jan 29, 2015)

paulw12 said:


> Maybe he didn't have bose? you need to ask him.
> A lot easier buying new stuff....
> I recon you have non-bose harness, I suggest you buy pc9-410 from my link
> The red input to headunit is taking live straight from your new live feed I assume, which is correct.
> ...


Ok thanks for all your help mate Cheers


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## sweatystt (Jan 29, 2015)

UPDATE. Ok ive now got things sounding good but im getting a big crack type sound when I turn on and change tracks etc through the speakers. Like its too loud. Any ideas?


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## asahartz (May 24, 2014)

That would suggest you need a ground loop isolator - you can get these from Maplins.

But I think you only have half the PC9-410 - there are two parts to this harness.

I've just pulled mine and photographed it for you, this is what it should look like:










Note that there are three plugs in the original wiring loom for the OEM Concert head unit, and the red one is not used.

The red plug in the PC9-410 connects to the phono pre-outs - this is the only way that the Bose amp gets input from the head unit and only the fronts are used (I've plugged in the rears just for neatness). The speaker outs from the head unit are not used.

The blue/white wire from the red plug in the PC9-410 is used to power the Bose amp, and must be connected to the blue/white (antenna power) wire from the head unit - I was able to do this via the other part of the PC9-410 harness adapter. If you are using the PC5 antenna adapter (I didn't cos I only use DAB) this must also be connected to the blue/white wire here.

Hope this helps.


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## sweatystt (Jan 29, 2015)

asahartz said:


> That would suggest you need a ground loop isolator - you can get these from Maplins.
> 
> But I think you only have half the PC9-410 - there are two parts to this harness.
> 
> ...


Thanks for the trouble pal very good of you. I've definitely only got 2 oem wiring not 3. I've got the red plug from the pc9-410 (phonos) plugged in to the only oem it will fit. Didn't have this earlier by the way which was half the problem! Obviously then the 4 phonos straight into the back of the stereo. I haven't used the other half of the pc9-410 as it doesnt seem to go anywhere. The blue and whites are also now connected together. All sounds clear and loud but ive got this 'crack' or 'pop' noise every time I change channel or track. Like the speakers are going to blow! lol I've not got a hum noise so will that be the ground you think? I take it the ground loop isolator goes I between where the phonos are plugged in?


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