A3 Euro tail light coding fowl up?

Discussion in 'VAG codes' started by drdrewusaf, Aug 22, 2010.

  1. drdrewusaf New Member

    Hello everyone,

    I have an American spec 2009 face-lifted A3. I replaced the tail lights with the European tail lights from oemplus.com. For the last week I have wracked my brain trying to get them coded correctly in central electronics. Oemplus doesn't have a coding reference and none of the internet seems to know how to code the newer 8P0 907 279 P central electronics module (instead of being 17/23 bytes it is 25 bytes - most of the internet guides are only partially accurate).

    The closest I got using only the first 23 documented bytes was to have the amber signal and one of the brake lights flash as turn signals. Being the "daring" individual I am I decided to try changing the 2 undocumented bytes. Byte 24 was set to HEX 64, I assumed this meant it was a dimming value and I was right...it sets the brightness of the LED rings as turn signals (it also allows them to blink). I set it back to 64, then moved on to byte 25. Bits 1-4 are the only bits that the module will accept as being set or unset. Bits 3 and 4 were set 1 and 2 were not. So I unset bits 3 and 4, and low and behold, the amber lights were the only things blinking...eureka. I went back to see which bit changed the setting and it ended up being bit 4. Bit 3 seemed to have no effect so I set it back - just in case.

    Happy with my lights working, I went to bed (it was around midnight). The next morning (still dark out) I started my car to find that 75% of the interior lights were "flickering" (this symptom did not exist before I went to bed). The 75% are the climate controls-including the LCD, the RNS-E's button lights, and the door lights. Also, the sunroof controls no longer light up. The dash pod, indicators next to the shifter, and the indicators on the light switch still work fine. The flickering seems to happen in a haphazard sequence, it is NOT completely random. I quickly changed the coding back to the "one brake light w/ the amber light" coding I had before, but to no avail - the flickering continues. I've run output tests and read the measurement values, but I can't see anything that shows this flickering. There's also no fault codes. I've also tried placing the original tails back in and recoding to the original but there was no change.

    Did I fubar my ECU or the Central Elec. module? Or maybe there's a continually running test sequence running? Also, it may have been an oversight on my part, but do you think the light switch needs to be replaced w/ the Euro version? Any suggestions on what the problem might be will help. I'm going to disconnect the battery today for an ECU reset and see if anything happens.

    Thanks for reading and any suggestions...


    Drew
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    PetrolDave Super Moderator

    If you have a genuine copy of VCDS it might be worth asking Ross-Tech for help on one of the many forums they are active on.

    They may ask you to submit a control module map to them.

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