I have no idea if everyone already knows of this but Karl from elsewhere has enabled ( and i have just done the same) this _ it's brillaint and means I do not have to go and buy LED brake lights with all the additioanl costs involced. so for what it's worth:

and thanks to Karl (Karls 3.0 TDI build thread | Audi-Sport.net)

"Not many updates on here for a while. Finally got the Hybrid turbo fully sorted and hopefully car will be remapped shortly.
Just been tweaking with VCDS after I read a post on here about enabling extra brake lights. seems a little daft only having 1 brake light bulb each side when you can have 3 On the Avant If you add 3 to the coding of the 4 channels 195,196,203,204 you enable the bulbs to work as brake lights as well. If you add 6 then they will flash with the indicators as they do in North America.
Not too sure about the saloon coding. Channel 195, 196 should be the same add 3. I think the coding shown below for 203, 204 for the saloon will make the lights flash with the indicators as well as act as brake lights.

Here's a summary of the coding to enable the middle and inner bulbs as brake for the B8 halogen:

Module 46 - Adaptation
Password: 16017

Sedan (Limo):

Channel 195: Left middle - 10753 -> 10759 (add 3)
Channel 196: Right middle - 10785 -> 10791 (add 3)
Channel 203: Left inner (on Limo also Fog) - 8778 -> 8775 (subtract 3)
Channel 204: Right inner (on Limo also Fog) - 8810 -> 8807 (subtract 3)


Avant:

Channel 195: Left middle - 14849 -> 14855 (add 3)
Channel 196: Right middle - 14881 -> 14887 (add 3)
Channel 203: Left inner (on Limo also Fog) - 14849 -> 14855 (add 3)
Channel 204: Right inner (on Limo also Fog) - 14881 -> 14887 (add 3)


Bulb out warnings:

Channel 181: 65535 -> 0 (rear halogen to LED conversion)
Channel 191: 65295 -> 0 (disable all rear bulb out warnings)
Channel 192: 3 -> 2 (disable licence plate bulb out warning)

Just enabled the extra brake lights on the left in this picture."