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Looking to tap into a power supply/signal...

Zak0123 Mar 28, 2016

  1. Zak0123

    Zak0123 Active Member

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    Happy Easter folks!

    Looking for a power signal for the remote input on my amp. I need one that switches on with the car but is not permanently live.

    I was looking at using the cigarette/power socket outputs, however these come on when the ignition is on which would unfortunately mean the amp would cut out when I turn the ignition off (the sub would cut out but the MMI would still be on = annoying)

    Ideally looking for something like the MMI which comes on when the keys are put in and does not switch off until the keys are physically removed from the ignition.

    So... Any ideas guys?
     
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  3. h5djr

    h5djr Well-Known Member Gold Supporter VCDS Map User quattro Audi A3

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    Hi Zak

    It is possible to change a fuse location in the fuse box so that the 12v sockets stay on all the time. I remember picking this up from a Golft GTI website some time ago and posting the details. Even Huntingdon Audi have used it several times after being asked about it by other customers. I will look back at my earlier posts and come back.
     
  4. h5djr

    h5djr Well-Known Member Gold Supporter VCDS Map User quattro Audi A3

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    This is what I was looking for:
    Fuse box for 12v socket.jpg

    If you look just to the right of the 2 15A fuses (the blue ones), you'll see a 20A fuse (yellow) that seems to be going between 2 rows of fuses. I looked up the fuse in the manual to see what it was, and it's the fuse for the lighter socket / 12V socket. The reason for this is because the fuse can be moved depending on whether you want 'on with ignition' or 'on permanently' mode for the the socket. As it's shown there, it's in its 'default' place of on with ignition only, but if you were to move it up half a fuse-length to be in line with the 30A and 40A fuses on the row above, it would be permanently on. I've confirmed with a multi meter that the contacts above the fuse are permanently on and the lower one (the one that the bottom of the fuse is currently in) is on with ignition only. The middle contact (that the top of the fuse is currently in) goes to the socket itself.
    Hope this helps!
     
  5. Zak0123

    Zak0123 Active Member

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    Hiya Dave,

    Thanks for the reply. I have read about this on another thread but my concern is that a permanent feed will drain the battery as the amp will be on constantly (the amp is 'powered' constantly but the 'remote wire' tells it when to switch on and off).

    I'm almost looking for a half-way-house between permanent-on and on-with-ignition. Something that will power up with the MMI would be perfect.

    Does that make sense?
     
  6. h5djr

    h5djr Well-Known Member Gold Supporter VCDS Map User quattro Audi A3

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    You could connect it to the socket as they are and just turn on the ignition whenever you want to listen to music. With modern cars I don't think there is any problem leaving the ignition on for a long time without the engine running.
     
  7. Zak0123

    Zak0123 Active Member

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    Cheers Dave, that's the one I've read about.

    You are right I'm not too concerned with killing the battery listening to it every so often with the ignition on, I'm just thinking that sometimes I might sit on the drive, switch the engine off and listen to the rest of the song for example, and in this case turning the engine off (aka switching off the ignition) would kill the amp but the music would still be playing. I could then switch the ignition back on but it's just a bit inconvenient.

    Not the biggest deal in the world I just thought I'd put it out there to see if anyone has any better ideas :)
     
  8. Zak0123

    Zak0123 Active Member

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    Any ideas on this guys? Has anyone used anything similar with their in-car cameras?
     
  9. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User MQB Platform

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    Turning the engine off will not kill the ignition it will return to ignition/accessory position. In older cars there would be 3 positions, ACC, IGN and Enginine start. I'm 99% sure that when I turn my engine off everything electrical remains live then when I remove the keys the screen drops and everything is then off. Got me thinking about it now ....

    In terms of draining the battery I've often had the ignition on for fairly lengthy periods at a time 30-45 minutes whilst doing VCDS mods.
     
  10. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User MQB Platform

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  11. Zak0123

    Zak0123 Active Member

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    Thanks for the reply Rob. Tapped into the bottom 20A and can confirm it only comes on with the ignition. Like you've said, tapping into the MMI would be perfect I just can't find a signal that will do something similar.

    I actually tapped into the MMI fuse according to the handbook but it was a constant source I.e. Not what I'm after.

    I've got my amp remote tapped into the 20A for now until I can find something better to tap into...
     
    Rob2k68 likes this.

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