Simple question; where is the TCM located ?
 

Hi,

im an a8 a8 noob here, i know in the a4 b5 the tcm is under the front passenger carpet, but where is it in the a8 ? and is it generally faulty

Location: Under hood next to ECM (in E box) in fresh air plenum chamber.

P.S.
Why TCM? What symptoms or codes?

I have not checked the codes yet (will soon though) but when it reaches the 4th gear, the gear engages and disengages (very violently, lol) and when it reaches 5th gear, it goes to neutral and the PRND432 gets all lit up (tranny fault). So I can drive it around fine if I leave it in 3.

There was a blocked water drain in the bulkhead (lots of water also), but the TCM seemed dry. I think i'l check the codes and maybe try another TCM to see if its the tranny or ?..

Buying a TCM might be a waste, esp if it's dry....sounds like the trans itself.
TozoM8 is the trans guy here...he actually rebuilds em. Get codes first and report back before spending any $$.

P.S. TozoM8 may not be on this forum. He's on these:
http://forums.quattroworld.com/a8/
http://forums.audiworld.com/forumdisplay.php?f=8

OK, got the codes, here they are:

Control Module Part Number: 4D0 927 156 KA
Component and/or Version: G5 01L 4.2l4V USA D32
Software Coding: 00002
Work Shop Code: WSC 00000
3 Faults Found:
17114 - Gear Ratio Monitoring: Incorrect Gear Ratio

17119 - Gear 5: Incorrect Ratio

P.S. I have not changed the tranny oil yet (the oil has been there for 150 000 to 220 000kms)... probably the next logical thing to do would be a filter + oil change ?

17087 - Brake Switch (F): Electrical Malfunction

The oil/filter change helping at high mileage is a subject of much debate...but most agree that it doesn't usually solve problems like you describe, unless the ATF is really low or a dented pan plugged your filter.
I highly recommend become a member of one of those other forums I listed and posting this info to TozoM8's attention...he's the trans guy.