JMB RetrofitsChris Nott
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  1. #1
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    No \"ignition on\" when installing aftermarket HU?

    Just thought I'd repost this one under a more searchable heading.
    Many of the newer Audi's are using more features on the CAN-BUS with their HU's, and thus "simplifying" wiring to the unit. Later models no longer seem to provide a separate remote on/ignition feed to the OEM HU, now adopting the CAN-BUS to send data to the HU to tell it that the ignition has been switched on, so please turn yourself on. What a great application of digital technology? As the old separate ignition supply really was showing its age [img]/ubbthreads/images/graemlins/grin.gif[/img]

    So when replacing the old dog with something that works properly and sounds fantastic, you are forced to poke the "ignition on" wire into the permanent live, thus having to manually turn off your HU everytime you leave the vehicle, with the resultant flat battery if you forget.

    If this is the case on your vehicle you will see from the black ISO connector that you are missing a few wires. Traditionally there are 4 or more (perm live, ground, ignition, remote on/power antenna).
    If you only have 3 on this block then you will need to perform this mod.
    Firstly locate your fuse box (drivers side end of the dash), prise off the cover. The fuse you need to locate is either no. 37 or no. 10, (varies depending on year, check on the back of the fuse box cover as this seems to be tailored to the car, the manual is generic and not always accurate).
    The fuse you need to locate is described as S-contact (radio) and should be 10amps. Bear in mind the fuses are upside down and back to front as the manual is for LHD vehicles.
    When you locate it, pull it out, and check with a multimeter that 12v is present with the ignition on, but disappears when you pull the keys out. If you don't have a multimeter, buy one of those 12v testing screwdrivers (very useful for 2.99).

    Now you need to access the wiring to the fuse. Unscrew the 2 Torx screws holding in the fuse panel. The panel is now held in via a couple of plastic clips.
    You now need to remove the drivers side dash trim. This is fairly easy, 3 Torx screws on the end (around the fusebox), then 3 more detailed below. The trim unclips at the top either side of the steering wheel. Unclip the wiring for the headlights and manoevour over the bonnet release and out.
    The wire to the load side of the fuse seems to be consistently red with a white stripe, shown below. Just wire tap onto it and feed the wire back up to the HU's ignition on lead.
    You will now have a HU that turns off when you take the keys out, just like the OEM unit. The only difference being that you can't turn the HU on without the keys.

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  3. #2
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    Re: No \"ignition on\" when installing aftermarket HU?

    Very useful. Thanks for the info. [img]/ubbthreads/images/graemlins/smile.gif[/img]

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    Re: No \"ignition on\" when installing aftermarket HU?

    Cheers, haven't tried doing it yet, but it explains quite a lot. Do you know off hand what the yellow lead does?? The cable coming up to the head unit but not used???

    Cheers

    Ben [img]/ubbthreads/images/graemlins/dancing.gif[/img]

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    Re: No

    If you have a yellow lead to the power block that's not used, then chances are you don't have this problem. This fix is for later A3's that only have 3 leads going to the power ISO connector (perm live, ground & remote on).
    The other connections on the power block are illumination (to dim with the dash), K-BUS, GA - GALA (speed sensitive volume) and MUTE for handsfree.

  6. #5
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    Re: No

    didn't work for me unfortunately, it kept the HU permentently on and the remote locking did no longer work, coz at the moment i take the key out and it turns off but when turned back on the HU has lost all settings and i have to re-enter my security no.

    Any Advice?

  7. #6
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    Re: No

    What didn't work?
    You have a permanent live which needs to connect to the permanent live to the HU (to keep the settings in memory).
    The ignition on connection is the switched 12v, so should be connected to the switched supply on the HU. Sounds like you have connected both supply cables to the ignition on connection, which means you will lose all settings when you take the key out.

  8. #7
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    Re: No

    Also worth noting that in the newer A4's (and I assume other models) the illumination feed is also on the CAN bus, so will need considering for many non OEM decks.

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    Re: No

    I thought the mod was meant to keep the head unit on apart from when you remove the key and keeping memory settings but when i remove the key the same thing happens as if i don't do the mod, Which is i have power with the keys in obviously but when removed it resets my HU everytime.

  10. #9
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    Re: No

    Matt, as Andy says it sounds like you have connected the permanent live and the ignition on the wrong way round into your Head Unit.

    I haven't got round to sorting the mod on my car yet, but I was considering grabbing the illumination input to the head unit from the glove box light feed, as this is only switched with the lights. Don't know whether this will overload it, but on my Head Unit the illumination feed just 'dims' the Head Unit so would only be some sort of low current switch internally.

  11. #10
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    Re: No

    Matt, you ony need to do this mod if you are missing the "ignition on" wire on the Black ISO connector going to the head unit. Seems to be late model A3's.
    From what you've said, you seem to already have the ignition on cable, so you don't need to do this mod.
    The problem you describe is the exact opposite. You have plugged the ISO connector into your HU, but your HU is expecting perm live on the ignition on pin and ignition on on the perm live pin. This is a common problem with Audi's & VW's. Your HU may have a switch on the top of it to reverse the wiring (I've seen this on Sony HU's). Otherwise you'll need to cut the wiring, either at the HU, or the Audi loom (HU's probably preferrable). Just cut the perm live, and switched live cables (usually yellow & red cables)and connect the perm live to the switched live, and the switched live to the perm live. (Use bullet connectors or terminal blocks)
    So you'll end up with red connected to yellow, and yellow connected to red. Sounds complicated but it is dead easy.

  12. #11
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    Re: No

    [ QUOTE ]
    AndyMac said:
    From what you've said, you seem to already have the ignition on cable, so you don't need to do this mod.
    The problem you describe is the exact opposite. You have plugged the ISO connector into your HU, but your HU is expecting perm live on the ignition on pin and ignition on on the perm live pin. This is a common problem with Audi's & VW's. Your HU may have a switch on the top of it to reverse the wiring (I've seen this on Sony HU's)..

    [/ QUOTE ]

    This was the cae in my A3 (1998)... Luckily the SOny wiring loom had bullet connectors on the perm live and switched, so that you could swap them over. Problem sorted in about 5 mins.

    Cheers

    Rich [img]/ubbthreads/images/graemlins/beerchug.gif[/img]

  13. #12
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    I'm in the same boat with this!
    The guy in the local car audio shop gave me a relay to put in between the power ISO connectors but this just doesn't seem to work either.

    Any chance you can give the more details about taking off the trim around the fusebox/steering wheel for running the cable?

    TIA!

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    This is for an A3 55 plate.

    I've just had a look at the manual at the fuse listings. There isn't one marked S-connect listed. Is there an alternative that I could tap into?

    The manual lists:

    10 is Selector Gate for an auto
    37 is seat heating.

  15. #14
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    No later models 51 onwards don't even bother giving you anything at the fusebox which will keep the HU on when you turn off the ignition, but turn off the HU when you remove the keys.
    For 51 models onwards you have to tap the feed from the ignition key switch, which is a bit more involved. If you don't mind the HU going off when you turn the engine off then just pick one of the fuses that is only live with the ignition on, like the aircon or main beam, then follow the instructions above.
    If you want a proper ignition on feed i.e. the HU stays on until you pull the keys out, then you need to wire in a relay. The trigger to use for the relay is under the steering column. Remove the trim under the steering wheel and you will see the main loom from the ignition switch running under the left side of the steering column. You'll see some black trunking protecting the loom. Release this trunking so you can get to the wires. You'll see a very thin red wire in amongst all the other thicker wires. This is the one you want.
    With the ignition off and the keys out, chop this wire and reconnect it with a small terminal block along with another wire that you can then run to the relay. Unfortunately the wire is so thin that you can't get a reliable feed using a piggyback connector.
    This is a very low current feed so you can't power the HU directly from it. Just wire in a 12v relay using piggyback connections from the perm live & earth at the HU and use this new wire to switch the relay on/off, then use the other side of the relay to power the HU. Sounds more complicated than it actually is, took me 30-45 minutes to do mine, but well worthwhile otherwise you need to have the keys turned to ignition on to get the HU to work when parked up.
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  16. #15
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    I'll have a look at doing it this way, thanks.

    Is there a quick "howto" on getting into the wires on the steering column?

  17. #16
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    There is a company out there doing CANBUS modules that will give you the power up signal as well as speed pulse etc for aftermarket installs in CANBUS cars.

    I don't have a link to hand but you should be able to Google it.

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  18. #17
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    Thought I'd let you know I got recommended a part at my local car parts shop.

    It's made by www.incartec.co.uk (part number 10-601) and connects between the power ISO connectors. It basically turns the stereo on and off when the ignition is on or off. Downside is that you can't have the stereo on when the engines off but the good side is that it only cost me 19.99 and no wires to cut.

  19. #18
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    Right-I have A4 2001 B6 and I faced same problem with the ignition wire.simply missing in iso connector. my radio without this "ignition" wire was switching it self off after a 1 hour.Prety anoing!!!so today i don it all so now my radio works as it sould. (ignition on=radio on / ignition off=radio off) the guy up there is right need to run extra wire but i used diferent fuse nr. 5 i think.Easy to do it but if you dont have basic skills with electrics you better leave it. ) ooooh by the way now i have new and shiny Blaupunkt Bremen MP76!!! see ya
    Last edited by dodo0903; 31st March 2008 at 22:24.

  20. #19
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    Hold on, can't you just wire up to connection point 75X near the fuse box? Why bother with extra boxes and gizmos?
    Certainly this is an ignition switched live as its where my boost gauge light is connected too.
    98 Noggy Blue S4 Avant - RS4 Suspension and ARBs - DTS - Miltek - 18" Nuvolaris - ECS Stage IV - 710n - Quickshift - AWE Vent Boost Gauge - MRC Custom Map - 315BHP with 355 ft/lbs

  21. #20
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    You can, but that will turn the HU off when you turn the ignition off. If you're parked up listening to the radio you have to have the ignition turned on. This mod is for people who want the proper turn on/off feature providing the same functionality you get with non CANBUS Audi's i.e. the HU stays on until you pull the keys out.
    As for boxes and gizmo's we're talking about a single 12v relay, no boxes and no gizmo's.
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  22. #21
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    Yeah I understand that. It was in reference to the post from "trailer". 20 for a box which does the same as connecting to the switched live accessory feed.
    98 Noggy Blue S4 Avant - RS4 Suspension and ARBs - DTS - Miltek - 18" Nuvolaris - ECS Stage IV - 710n - Quickshift - AWE Vent Boost Gauge - MRC Custom Map - 315BHP with 355 ft/lbs

  23. #22
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    Ahhh got it, sorry.
    "How to tear apart the ties that bind, perhaps fcuk off might be too kind"
    Alex Turner

  24. #23
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    To me the 20 relay was easier just to chuck into the wiring loom. I appreciate that a lot of you would prefer to go with the wire to the ignition/fuse box option but at least there's an option if you don't.
    A3 2.0TDi Quattro Black Edition Sportback : Phantom Black

  25. #24
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    Just had to do this, wanted to say thanks to Andy, very helpful, and my stereo now functions properly

    Cheers,
    Dave.

 

 

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