Audi and Electricals (Kinda Long) C5/A6

Thu Sep 23 06:49:32 PDT 2010

This was recently posted and would be good for you to read;

http://tinyurl.com/35orrak

What Chris and Cody said is on point, more than often a thorough visual
inspection will reveal the root cause of the problem whether its moisture or
something cut or loose.. besides if you are not to sure what you are probing
you could wind up compounding the situation.

I'm also not fully sure on what the symptom you describe is. If its the 'P R
N D 3 2' display on the cluster, well, those clusters arent the best..

Also, if not from my local shops, I have purchased bentley manuals from a
guy that goes by "bimmerzone" on ebay, with good experience. You need the
correct manual.

-brian

On Wed, Sep 22, 2010 at 1:50 PM, mkb <mkb125 at yahoo.com> wrote:

> Chris,
>
> Yep, I've checked this and it appears dry.  I'll be checking again to
> confirm.
>
> I was able to pull the plastic box and get to the actual TCM.  The only
> seal I
> found was where the bunched wires go into the box and the TCM.  Now that I
> recall, I did find pieces of broken glass at the bottom which leads me to
> believe that the carpet must have been pulled up at some point and some
> water
> might have gotten in.
>
> Anyway, good info from both you and Cody.  Thanks!
>
> --
> mohammed
> 99 a6 2.8q avant
> 97 1.8tqa
>
>
>
> ----- Original Message ----
> From: Chris Semple <chris at force5auto.com>
> To: mkb <mkb125 at yahoo.com>
> Cc: quattro at audifans.com
> Sent: Tue, September 21, 2010 11:27:41 PM
> Subject: Re: Audi and Electricals (Kinda Long) C5/A6
>
> 30 is battery positive in Bentley speak. One note from the KISS school of
> auto
> tech, before chasing wiring connections with a meter, pull up the RF carpet
> and
> have a good look at the TCM(trans computer). That series of cars isn't
> known for
> electrical troubles, and it does seem that your issue is "narrowed" down to
> the
> trans circuit. They are however, known for flooding out the floorboards
> which
> includes the TCM on the RF and the CCM(comfort/conv module) on the LF. Audi
> half-engineered the plastic box containers for these ecu's, which means
> that
> they created a box for these things to live in(good) but didn't weatherseal
> the
> box or provide drains in the box(bad). So even a smallish amount of water
> getting in there will have a hard time getting out. I've used baggies and
> shrinkwrap as a preventative measure on some cars. Inspect the TCM for
> water
> damage, including the harness. I've sold plenty of TCMs, occasionally with
> harness pigtails. Even bought cars from dealers who were sure they were
> "junk"
> :)
>
> -Cheers
> -Chris Semple
> Concord NH
> '84 4000q
>   '08 E350 Club
>       '04 F350 DRW
> > 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
> >
> >
> >       _______________________________________________
> > quattro mailing list
> > http://www.audifans.com/mailman/listinfo/quattro
> > http://www.audifans.com/kb/List_information
> >
> >
>
>
> --
> -Chris Semple
> Force 5 Automotive
> 223 South Main St
> Concord, NH, 03301
> 603-223-6700
> www.force5auto.com
>
>
>
>
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