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Factory LED DRL Failure?

Discussion in 'A3/S3/Sportback (8P Chassis)' started by Arrowhawk, Jul 26, 2013.

  1. Arrowhawk
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    Arrowhawk New Member

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    [Jul 26, 2013]
    Hi,

    Today my dash bulb warning came on showing a fault on the right DRL / sidelight. I have checked and none of the LEDs are illuminating on the right hand side.

    A scan with VAG-COM gives the fault below in the Central Electrics.
    The car is a 2009 A3 Sportback TDI Quattro Black Edition, so has factory Xenon and LED DRL lamps.

    The only results I can find from searching the fault code are from people who are carrying out LED retrofits.

    Has anyone experienced this before? I have read that if an LED unit fails the complete headlight unit needs to be replaced, so hoping there is something else to check first! ELSA Current Flow diagram shows an LED control unit inside the headlamp and two wires from the central electrics to this - I didn't want to put a meter across the wires in case they are running CAN rather than simply putting voltage to the LEDs, as not sure if the dimming etc. will be controlled by the central electrics or the LED control unit.

    Cheers.
    #1
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  3. Artimus
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    Artimus Short Back

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    [Jul 27, 2013]
    Have you tried any fixes yet? like pulling the plug to look for corroded contacts. HID still working okay?
    #2
  4. NHN
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    [Jul 28, 2013]
    Didn't we discuss this before or was it another member with the same problem?

    Just meter the pins 10/12 & ground being 7, do a comparison of the other side to check readings as this uses the same pin numbers.
    #3
  5. Arrowhawk
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    Arrowhawk New Member

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    [Jul 29, 2013]
    Hi,

    It could have been another member, although I couldn't find any similar thread. Mine rather typically just went wrong on Friday afternoon before I was heading away for the weekend!

    All of the connections look shiny and wiring seems to be in tact, and everything else in the lamp is working fine - it is only the LEDs that are out.

    I have been out with the multimeter tonight and got the following results -
    With the DRLs or sidelights turned on the voltages are similar enough for me to believe that the headlamp unit is at fault and the central electrics unit and wiring are fine, although I can't understand why with the DRLs and sidelights off there would be 5V at pin 12 of the left lamp but 0V at the right one?

    Assuming the headlamp unit is faulty, is there anything that may be repairable inside? Seems strange for all of the LEDs to blow at the same time, so I presume it is some LED control unit in the lamp that has gone. If it wasn't a case of removing the bumper etc. to get the lamp out I'd just go ahead and remove it to take a look, but didn't have time to get the bumper off tonight.

    Cheers.
    #4
  6. NHN
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    [Jul 29, 2013]
    Well with those readings, next step is to swap the lights over & test, but the voltage difference maybe part of the cold diagnosis system & the fact its already detected an issue with the right side & thus isn't applying any voltage.

    I wonder if the voltage shows up as 5.7 when you clear the fault with vcds in 09 for the right headlight, as affectively this resets the system.
    #5
  7. Arrowhawk
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    Arrowhawk New Member

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    [Jul 29, 2013]
    Thanks for the quick reply. I thought the same about the voltages, but by the time I measured the voltage at the left headlight the fault for it was already showing up in VCDS too due to having the plugs disconnected. I did try resetting the faults afterwards and rechecked, but the results were still the same.

    Looks like its time to swap the lamps, or if I can get hold of the correct plug housing handy it might be easier to rig up a test loom to extend the wiring over to the other side of the car to test in place without removal - I should get away with just extending over pins 7, 10 and 12 to test the LEDs I think.
    #6
  8. NHN
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    [Jul 29, 2013]
    Yeah the connectors can be bought of audi aswell as the pins & sounds like a plan, but you could take bumper of quicker than getting those parts.
    #7
  9. Arrowhawk
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    Arrowhawk New Member

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    [Aug 1, 2013]
    Just to update, I got the pins and plug housings yesterday and made up a loom to test the headlamp and wiring on the other side without removal.

    Headlamp unit is definitely at fault, it must be the LED control unit that has gone in it, so looks like a replacement headlamp is the way forward. Not a cheap fix unfortunately!
    #8
  10. NHN
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    [Aug 3, 2013]
    What's the part number of your headlight?
    #9
  11. Arrowhawk
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    Arrowhawk New Member

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    [Aug 5, 2013]
    Headlight part number is 8P0 941 030 BF.
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  12. NHN
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    [Aug 5, 2013]
    The lights £374 from audi mate, we maybe able to save a few quid & get delivered to you, but we're not talking vast amounts, but we can try & help.
    #11
  13. Arrowhawk
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    Arrowhawk New Member

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    [Aug 5, 2013]
    Thanks for the offer, can get a bit of discount from Audi locally though so will prob go down that route and save any hassle with delivery etc.
    #12
  14. Chienmetallique
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    Chienmetallique New Member

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    [Sep 26, 2013]
    I have just had the same happen, where is the control unit to swapover and check?
    #13
  15. NHN
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    NHN Retrofitter - Audi - VW - Skoda - Seat Site Sponsor VCDS Map User

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    [Sep 26, 2013]
    On bottom of headlights.
    #14
  16. Chienmetallique
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    Chienmetallique New Member

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    [Sep 27, 2013]
    Not easy to get to is it. Any chance there is a link to a guide with images on how to access this?
    #15

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