Audi and Electricals (Kinda Long)

[mkb]

Hi Folks,

So I'm trying to sort out my A6.  Seems to have some electrical issues most of 
which I think I have sorted out.  I think I've got one major issue to resolve 
but I'm no electrician and I'm having a tough time trying to understand wiring 
diagrams but I think I understand a little more than I did a few weeks.

So here's the situation.  My VAG-COM reports the following:
00668 - Supply Voltage Terminal 30
31-00 - Open or Short to Ground

This is reported by the transmission control module (TCM) on the VAG-COM so I 
assume that the TCM is not getting enough supply voltage.  Why do I say this?  
Because the transmission range display on the dash lights up.  I can reset the 
code and the display shows correctly until I restart the car.  I also know (I 
think) that Terminal 30 is the negative (right?) post from the battery that 
supplies the various components with power.  I assume that all the other 
components are OK because only the TCM is throwing the open or short to ground 
(right?).

Now, I could clean the battery ground and the ground strap on the starter, but 
since I only see the TCM throw an error, I assume that the ground connections 
are good.  So then there must be a wire from the battery that supplies the TCM 
with voltage and that must have a short somewhere from where it connects from 
the power source to the target module, the TCM in this case.

Right now, I'm looking at a wiring diagram for a auto tran with tip from my 
Bentley for an A4 (repair manual page number Y429).  I'm assuming it's going to 
be pretty much the same if I look under the same engine code and year.  And I 
see a red wire from terminal 30 go to A40 which is a plus connection in the 
instrument panel wiring harness which then goes to T15g/11 which is a 15 point 
brown wire connector station right, A-pillar.

Folks, bear with me.  I've been trying to complete this post for the last two 
hours referring to the Bentley and trying to understand and write something down 
without sounding like an idiot.  If you've read this far, I appreciate it.

OK, so after some hours of thought, I think my plan of attack is to go to the 
right side A-pillar with a MM, locate T15g/11 (15 point brown connector) and 
check the circuit there since it's probably the easiest to get to.  I don't 
really know how to do this, but I figure I'll sleep on it and it'll come to me.

Folks again, I apologize for this long, rambling post.  Hopefully, someone will 
read it and say "No, you're a complete moron, you're totally off track" or, 
"Yeah, that seems about right" at which point I'll change my strategy or 
continue on with plan this w/end.

--
mohammed
99 a6 2.8q avant
97 1.8tqa