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Audi A3 after-market head unit - help where is the battery power lead ??

Discussion in 'A3/S3/Sportback (8P Chassis)' started by solowkey, Oct 17, 2013.

  1. solowkey
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    solowkey New Member

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    <div>I looked into this in some detail&nbsp;and acquired all I was advised I needed
    before hand but I have had a nightmare trying to sort so far have made little
    progress.</div>
    <div>&nbsp;</div>
    <div>I have an audi a3 2003 , the later model (8p I think) it has audi symphony
    2 double din tape / in dash cd changer fitted , and has bose system front and
    back.</div>
    <div>&nbsp;</div>
    <div>I have done car audio installs before and had no trouble as it all makes
    sense to me , this doenst.</div>
    <div>&nbsp;</div>
    <div>So I managed to get the symphony out (shredding my fingers) and installed
    my new fascia (singe din) with cage for my stereo, confusion starts with
    cables.</div>
    <div>&nbsp;</div>
    <div>&nbsp;</div>
    <div>&nbsp;</div>
    <div>I have the ct51&nbsp;– au01 that is always recommended , I also have the aerial
    adapter </div>
    <div>&nbsp;</div>
    <div>my existing stereo I want to fit is a single din Sony, I have the sony to&nbsp;
    std iso connector </div>
    <div>&nbsp;</div>
    <div>&nbsp;</div>
    <div>Ok so 1st thing I want to do is get power to the unit , no chance, the power
    half of the iso connector which just goes straight to the iso power cable from
    the audi doesn’t match up, (looking at pin outs on here <a title="http://pinoutsguide.com/CarAudio/car_audio_iso_pinout.shtml" href="http://pinoutsguide.com/CarAudio/car_audio_iso_pinout.shtml">http://pinoutsguide.com/CarAudio/car_audio_iso_pinout.shtml</a>&nbsp;)
    I have&nbsp;8 ground, 7 +12v ignition,&nbsp;5 aerial power and&nbsp;4 battery&nbsp;– these are on
    the sony side of the hardness&nbsp;, on the audi side I have 7, 8&nbsp;and 1 ) so I get no
    power.</div>
    <div>&nbsp;</div>
    <div>I need a direct from battery power but its missing from audi harness , what
    happens here ?</div>
    <div>&nbsp;</div>
    <div>&nbsp;</div>
    <div>&nbsp;</div>
    <div>I'm not sure I have all connections in my car , I pulled off two aerial
    connectors , one is std so I don’t see why I needed adapter - &nbsp;one iso connector
    form the bottom (as detailed above ), nothing in middle iso connector, nothing on
    side the one, the top one is made up form two different plugs, blue section looks
    normal mini iso but black bit looks like its had the original end cut off at some point and there is
    a cable joining the two ? sounds weird and tbh I cant understand how the
    connectors I have to play with are going to get any signal to the bose ? I
    literally have power&nbsp; with SCV cable in , 2 aerials and the top plug of witch
    only the right hand side (for blue mini iso plug)section has in pins in on the ct51-au01 and from what I
    have read these are for CD changer ?<br><br>Please help , im sure i can do it if i can just get power to the head unit - is the audi iso not std ??<br><br>I surely don't have to run a new lead form the battery do i ?<br><br><br></div>
    #1
  2. JohnE
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    JohnE Active Member

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    The Audi harness does in fact have direct battery power, that's all it has. It's the one on the "power" ISO - what you don't have is switched ignition because the OEM Audi unit gets that (and SCV and Illumination) from the CAN BUS.

    Capture.JPG
    #2
  3. solowkey
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    solowkey New Member

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    OK thank you that explains a bit,gives me some idea (which is the can bus btw ?) So i need to get a switched ignition live push it through the audi iso where the battery live should be then swapped over with the switched and battery lives in the ISO coming from my sony.

    I can follow this but still have two questions, where do i get the switched live from and why is audi iso pin outs non standard, i thought the idea was to make fitments universal ?

    oh and one more from the diagram, i see the pin that is usually SCV is marked BOSE , i have this pin coming from my audi power harness what does it need to connect to as im sure my sony wont recognise or make use of this connector
    #3
  4. pablo
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    pablo Member

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    think the bose wire is just a remote feed to turn the amp on no?
    #4
  5. JohnE
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    JohnE Active Member

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  6. JohnE
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    JohnE Active Member

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    BTW - my Connects2 Interface doesn't mimic the Audi radio power perfectly - it does do IGN on but it doesn't provide power when the ign is off and the key still in the barrel. I queried this with Connects2 and they confirmed it doesn't use the Audi signal, it obtains "IGN" by using a voltage difference
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  7. solowkey
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    solowkey New Member

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    Thanks for the input guys. i have now got it fitted and working.

    The ISO connection is pretty useless in this application i had to modify every cable on it as follows


    -swap over the cables for battery live and ignition live as audi one is in wrong place (luckily my sony ISO had bullet splitters on both live cables so that was an easy swap)

    -bring ignition live from fuse box. for this i need a couple meters of cable, i used 27 amp but much too thick really the, dual fuse adapter, a selection pack of bullet connectors and a 5 amp fuse - this all cost 15 quid from halfords (although they dont actually sell the dual fuse adapters but they use them to fit stereos so they had a box full in service area , guy put on through for 2 for me). stripped cable ends put larger bullet on one end to plug into dual fuse adapter, plugged fuse adapter into fuse socket 41 (rear wiper)plugged 15amp fuse i removed into fuse adapter, put my 5 amp fuse in teh piggy back adapter, put smaller bullet on the other end and fed under the cowling to stereo area(it was a pain as i didnt remove cowling, i used the remaining cable i had and fed it down form setero housing, tied it to my new ignition live and carefully pulled it back up. T%hen just plug it into the bullet coming from the ignition live on the stereo harness.
    -ground for the ct51-au1, i couldnt see anything to tack this to so i cut the ground between iso and stereo and creted a bullet junction, then put other side of connector on the ground from ct51 - plugged together
    - aerial, thought this would be easy as it looked like i could just push this into the audi iso connector no chance i tried and tried but i was more likely to break it i think - so had to cut the aerial power between stereo and ISO (same as i did with ground), putting the two ends i had cut into the one side and the power from the aerial adapter/booster into the other - connected the fakra cable to one end ready to connect up now.
    -amp remote on , blue cable from ct51 , put bullet on, connected to bulleted amp remote power lead on my stereo,


    So pushed in the new fascia and stereo cage, i have my power iso which is bringing battery live and ground only, i plugged in my ground cable from ct51 using the new bullets i put on , plugged the aerial adapter into its new bullet connector, and my new ignition live into the waiting ignition live bullet on back of sony harness, connect aerial - no wait its the worng connection now : ( i need the long male plug type for my stereo , and this has the shallow circle with pin in the middle - i pushed it all in without connecting aerial that can wait.

    So its working fine, balance , fader etc is good , all speakers work and no popping at all - however quality isnt that great, maybe because its louder but keeping max to about 21 sees little distortion, stereo goes up to 52 but starts to sound terrible before it reaches , but this stereo has many sources so im sure it still needs playing with, need to get the aerial adapter and rip it all out again for that, and i managed to get some scrapes on the lower button panel belwo the stereo (where warning lights are) so watch out for that -it what i get for struggling on site not knowing what im doing for 2 days lol looks easy enough to replace if it annoys me though.

    So i thought i was prepared, but no i had to spend 55 on adapters and work from no instructions, and even then i had to cut 2 cables and add bullet sockets, add bullet connectors to 3 more cables, install a whole new fused ignition lead and would have had to cut 2 more cables if my iso lead didnt already have splitters on - not exactly plug and play as i was expecting, my old car was so much easier, one cable click.

    Anyway just wanted to put an end to my story , last night i had no idea what i needed to fix , it should be a bit more apparent that the audi iso is wired wrong and that you will need to install new cables and cut cables i had been given impression from most places this was not required

    After all that , i think the original HU sounds better - but i now have the connectivity i wanted and can listen at reasonable quality and the cd player actually reads discs all the time, but i wont be needing any now i have bluetooth.

    next will be looking at speaker / amp upgrade possibilities i think, or it might be back to a factory unit but hopefully one with better connectivity and a working cd player .
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  8. JohnE
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    JohnE Active Member

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    Glad you got it sorted.
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