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Sportback rear LED's - coding should be 36 or 48

Discussion in 'A3/S3/Sportback (8P Chassis)' started by danb986, May 23, 2011.

  1. danb986
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    danb986 In awe of VCDS

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    Just a very quick question.... I'm off home to fit my new rear LED's in a bit, but after looking at the coding listed on asn, there seems to be some variations with part of it.

    In some cases it says that Byte 12 to Dec should be 36, but some say it needs to be 48 to make it bright enough to match the inner part on the boot lid.
    Can anyone answer this for definite. If I have to make it brighter then will it shorten the life of the LED's?

    Thanks,
    Dan
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  2. c_w
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    c_w Active Member

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    Mine's set on 36, on 48 the outers become that little bit brighter than the inners.
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  3. danb986
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    danb986 In awe of VCDS

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    Thanks for the input C_W.
    People have said that the outers were too dim on 36, but they do seem quite bright on 48. Is it possible to put in any value you like in this box? I mean could I settle for a 42 if I think that looks better in my case?
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  4. LWNY
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    LWNY Member

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    The inners, when hooked up the the license plate lights, are basically 100% fully on, so I presume anything below 100 on the outer will make it dimmer than the inner tails.

    I did some light measurement of just the light tube on the inner when it was set to 36 and it is around 2 Fstop lower than the inners. You think it would look much darker, but apparently it looks similar enough. Somebody with me had theirs set to 42 and I thought it looked a smidgen brighter than the inner in daytime, so I set it to 36. Maybe I should have set it to 48.

    Plus, when I pointed the camera at the outer, I could see some sort of flickering on the camera's video display. I guess they lower the brightness by blinking it on and off real fast, to fast for our eyes to catch, but the camera, which is capture snapshots of the image to display, apparently captures various on and off stages of the LED.
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  5. danb986
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    danb986 In awe of VCDS

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    Wouldn't setting it to 48 make it even brighter than the other car that had theirs set at 42 though? Because you thought 42 looked a tad bright so why would you think 48 might be better for you than 36?
    (I've probably got it the wrong way round in my head).
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  6. LWNY
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    LWNY Member

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    42 only looked a tad bright when comparing in daytime, when both looked kind of barely lit. It was only when I stared at them after dark did the outer look a hair darker than the inners. The I confirmed it with my camera's exposure meter, setting it in macro and getting as close to the tube as I can until it filled the whole screen.
    Last edited: May 24, 2011
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  7. danb986
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    danb986 In awe of VCDS

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    That's a clever way of testing it. I think I'll turn mine down a bit then. I thought 48 was a bit bright tbh, but I only looked at it when it was dusk so I might try them in daylight and also at night. Thanks for sharing your results.
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  8. NHN
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    NHN Modmetractor

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    This is exactly why I always wire in as per oem as the number plate lights arent controlled via the same circuits hence differences, which is why they link inner/outers through outer wiring, the prism design also doesnt help the led's transfer the lights properly.

    The on/off flickering is probably PWM circuits, but only high frame rate cameras can pick this up usually.
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