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Number Plate Bulbs

Discussion in 'A3/S3/Sportback (8P Chassis)' started by gazcallyt, Sep 4, 2010.

  1. gazcallyt
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    gazcallyt Member

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    [Sep 4, 2010]
    Guys,

    New to the forum after purchasing an 05 plate sportback sport, also new to audi's.
    Been replacing the front sidelight bulbs and number plate bulbs for led's, the front sidelights I replaced with canbus friendly ones off ultraleds which work a treat, no errors, I forgot to get canbus friendly number plate leds, as a result I got the usual flicker and off it went, I managed to get them work but only when a normal bulb was used alongside the led, decided to put the originals back in, but neither of them come on now, just get the message that the bulbs are out on the dash, double checked the connections on the bulbs and all seem well, seems like the system has got confused, even tried the battery off for ten mins, no difference, any pointers ?
    Also had it on a diag machine today and it flags up fault in circuit, voltage on that circuit is just under a volt, tested the bulbs and they are fine, so something is not happy.

    Cheers

    Gaz.
    #1
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  3. Smoothie
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    Smoothie Active Member

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    [Sep 5, 2010]
    hmm thats a weird one mate, hopefully someone will be along that can help you
    #2
  4. gazcallyt
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    gazcallyt Member

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    [Sep 7, 2010]
    Me too, got me baffled at the mo.
    #3
  5. v1raj
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    v1raj Member

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    [Sep 7, 2010]
    Have you attached resistors to the light?

    I did this mod last week and mine wouldnt work without the resistors in. No problems after that.

    I'll get some pics if needed.
    #4
  6. mike foster
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    mike foster Fossie VCDS Map User

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    [Sep 7, 2010]
    Maybe you have to clear the fault on the diagnostics before they will work.

    Can I ask which of the three choices of LED sidelight bulbs you got - 1 at each side, 2 at each side or 1 at each side and 2 at the top ? I got some with 1 led at each side and needed to put resistors on them to get them to work. They also failed the MOT because the testers eyesight said they gave out a blue light which was not acceptable !!!
    #5
  7. gazcallyt
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    gazcallyt Member

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    [Sep 8, 2010]
    The front sidelights work fine they have built in resistors, they are the ones that have two on the side and two on the top, these worked a treat first time round.
    As for the rears, I'm exchanging the non resistor type for the ones that have built in ones which I should of ordered first time round, the problem is that the fault has been cleared yet it will not light any bulb even the orginals, it is though the system stills thinks the bulbs are out/blown even when the fault is cleared.

    Gaz.
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  8. PH1L
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    PH1L Gievf Buckets VCDS Map User

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    [Sep 8, 2010]
    clear the faults bud, then try the bulbs the other way round i suspect youve put them in the wrong current flow direction, being leds these would not accept power and confusethe system
    #7
  9. mike foster
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    mike foster Fossie VCDS Map User

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    [Sep 8, 2010]
    Do you still only have < 1 volt across the two terminals with both original bulbs in place ?

    If so then I think you will need an expert like NHN on this forum to help because the central electrics module would seem to have got seriously confused !

    Don't think there is a specific fuse just for number plate lights - has anything else stopped working ?
    #8
  10. Smoothie
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    Smoothie Active Member

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    [Sep 8, 2010]
    V1RAJ - post some pics, is yours as bright as this, mine below:

    [​IMG]
    #9
  11. gazcallyt
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    gazcallyt Member

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    [Sep 8, 2010]
    I wish they were that bright, I took them both out, I'm just trying to get the old bulbs to work again before attempting to put some other led's in.
    As for current flow yes this would affect the led bulbs but not the originals, I haven't measured the voltage with the bulbs in, surely if had 12volts there the bulbs would be lit, I have looked at fuses none blown, there isn't a specific fuse just for number plate lights, there is only a 40amp fuse for left hand side lighting and another for right hand side lighting, and another for interior lights, everything else seems happy as larry.

    Gaz
    #10
  12. v1raj
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    v1raj Member

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    [Sep 8, 2010]
    As requested, here are a couple of pics:

    Number plate lights with LED bulbs and resistors in place (resistors were soldered in afterwards):
    [​IMG]

    How they look:
    [​IMG]

    Pretty happy the results. Makes the rear look a lot better.
    #11
  13. gazcallyt
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    gazcallyt Member

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    [Sep 8, 2010]
    Thanks guys for rubbing it in, will hopefully get to the bottom of mine and at least get some light back there. Candles are looking good at the mo.

    Gaz.
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  14. Smoothie
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    Smoothie Active Member

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    [Sep 8, 2010]
    sorry for getting off topic mate...hope you get it sorted
    #13
  15. gazcallyt
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    gazcallyt Member

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    [Sep 9, 2010]
    No probs, glad to see they will be worth the effort when I get 12v back there.

    Gaz.
    #14
  16. v1raj
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    v1raj Member

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    [Sep 9, 2010]
    lol not trying to rub it in at all mate, just showing you what you have to look forward too ;)

    As been advised, if you have vag-com, get the fault codes cleared and try again.

    Let us know how you get on bud.
    #15
  17. scottie123
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    scottie123 (&#9679;&#814;&#814;&#771;•&#771;) (&#9679;&# VCDS Map User

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    [Sep 9, 2010]
    You may want to check the bulb holder. They are the worst design in the world, and can sometimes have a very poor connection.

    In the end , I bought new bulb holders, as I got pissed off with the number plate lights going off and on when ever they wanted.

    ~May be worth trying to connect the bulb without the holder, so you can eliminate the bulb holder as the problem. Just use a couple of wires to connect the bulb to the contacts in the housing.

    Also, to make things easier for you, a lock and unlock from your keyfob should be adequate to reset the error and return power to the lamps. Will make it easier for you when trying the bulbs and connections.
    #16
  18. gazcallyt
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    gazcallyt Member

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    [Sep 9, 2010]
    Cheers guys, will eliminate the bulb holders tonight, will also get the multi meter back there to see if the voltage changes at all.

    Gaz.
    #17
  19. gazcallyt
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    gazcallyt Member

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    [Sep 11, 2010]
    Right tested everything and its got to be the control unit to the lights I am only getting 0.60 volts with the lights on, all faults cleared and still not reading 12 volts, even with the lights off there is 0.45 volts at the terminals.

    Gaz.
    #18
  20. Smoothie
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    Smoothie Active Member

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    [Sep 11, 2010]
    so what does this mean mate? new control module?
    #19
  21. gazcallyt
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    gazcallyt Member

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    [Sep 11, 2010]
    Looking that way, will try and trace it back, keep you posted.

    Gaz.
    #20
  22. scottie123
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    scottie123 (&#9679;&#814;&#814;&#771;•&#771;) (&#9679;&# VCDS Map User

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    [Sep 11, 2010]
    Bit of a long shot, but have you trapped a cable somewhere when routing around . It may be possible that a cable has been damaged and is dragging the 12v down to ground which would you give you a very low voltage reading
    #21
  23. gazcallyt
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    gazcallyt Member

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    [Sep 14, 2010]
    Scottie,

    Haven't really had a route around to be honest to trap a cable, its booked in audi in a weeks time, see what they come up with, in the mean time just waiting for me new haynes manual to arrive so at least I can get a circuit diagram for it to see where the feed actually comes from.

    Gaz.
    #22
  24. gazcallyt
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    gazcallyt Member

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    [Sep 15, 2010]
    Right peaked at the wiring diagram for the lights basically one side of the circuit goes to earth and the other goes to the control module which controls all of the lights, now for the interesting part the feed that supplies the number plates also feeds what looks like the light switch illumination, now this works, so head scratch well and truly on, will have to wait to see what audi come up with as its stumped me.

    Gaz.
    #23
  25. scottie123
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    scottie123 (&#9679;&#814;&#814;&#771;•&#771;) (&#9679;&# VCDS Map User

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    [Sep 15, 2010]
    If that is the case, have you tried testing between to the light switch and number plate section for continuity etc.
    Just to purely eliminate the basics.
    #24
  26. gazcallyt
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    gazcallyt Member

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    [Sep 16, 2010]
    Scottie,

    Haven't tried that yet, going to test the earths tonight to make sure there is no voltage leaking to it.

    Gaz
    #25
  27. gazcallyt
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    gazcallyt Member

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    [Sep 23, 2010]
    RESOLVED AT LAST

    The metal prongs on the bulb holders were not touching the contacts on the car, instead they were been lifted up by the plastic in between the prongs, little bit of bending later, jobs a good en, now to get the leds in her.
    Cheers to all for guidance.

    Gaz.
    #26
  28. Smoothie
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    Smoothie Active Member

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    [Sep 23, 2010]
    ahh thank god you got sorted mate, let me know what way you go about installing the LED's
    #27
  29. scottie123
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    scottie123 (&#9679;&#814;&#814;&#771;•&#771;) (&#9679;&# VCDS Map User

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    [Sep 23, 2010]
    :yahoo:
    #28
  30. Smoothie
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    Smoothie Active Member

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    [Sep 23, 2010]
    Someone was on to something
    #29
  31. gazcallyt
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    gazcallyt Member

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    [Sep 24, 2010]
    They were, cheers scottie, I even checked them how many times, it was only when I decided to take the bulbs out, and look very close at where the prongs were ending up I spotted it.
    As for LED bulbs, probably end up putting the normal led festoons in with resistors across, what is the recommended resistor ?

    Gaz.
    #30
  32. b19ctr
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    b19ctr The King of Cannock

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    [Sep 24, 2010]
    Gaz not sure if your interested but I've got a set of festoons and resistors ready to go there yours for a £5 if you want them drop me a pm.

    Chris
    #31
  33. heeman10
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    heeman10 Audi driver since Dec 08

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    [Sep 25, 2010]
    Mine did this when I fitted my LED bulbs a few months back, crappy little tangs!
    #32
  34. t0ph0id
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    t0ph0id Member

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    [Jul 5, 2012]
    I just had this exact same problem. Thanks to this thread it's solved. :rockwoot:
    #33
  35. OVRA3
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    OVRA3 Well-Known Member

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    [Jul 5, 2012]
    I had this problem too but never managed to get the LED's to work so put the orginal bulbs back in :crying: bit nervy about trying again as it took ages to get them working again..
    #34
  36. t0ph0id
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    t0ph0id Member

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    [Jul 5, 2012]
    All I did was ever so slightly bend the two connector prongs so the stuck up a bit further to make contact properly.
    Give it a go.
    #35

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