New S6 Owner - An intro and help needed.

A6 All/ S6 All
#1

Hi Guys,
Love the site and it’s resources.

I just bought an 07 S6, 130k miles - it came at the right price so I thought “what the hell!” I knew it’d got a few issues just from my inspection and test drive.

A small intermittent misfire higher in the revs, no doubt plugs, coils and/or injectors. I’ll get around to carbon-cleaning in due course.

My first issue is to get it running - it churned a little before starting which I put down to an incorrect battery and it being sat. However, once I got it home and looked a little further I discover the battery negative cable an especially the bolt attaching it to the battery control unit is really hot - sufficient that it’d charred the trunk cover directly above! Looking closely, I could see arc marks on the cable BCU bolt. My guess is that ignorant to the Ways of Audi, the seller had jumped or charged the flat battery directly off the battery terminals, probably frying the BCU in the process?

I got my shiny new VAG-COM, hooked it up but not altogether sure what I should be looking for to confirm anything.

I’m guessing I need a new OEM spec battery, BCU and recode appropriately and then hopefully discover the rest of the joys awaiting me…

Any help or suggestions MUCH appreciated.

#2

If your electrical system is currently working ok, and the battery holds a charge when parked for a while, I think whatever happened was a 1-time thing, you’re probably right about the battery charger and/or jumping. You said it was hot, do you mean it was hot WHILE you inspected it, or just that there was evidence that it was hot at some point in the past?

#3

It was scorching hot (too hot for my hand, enough to scorch the trunk liner directly above!) when I checked it back at home. It was still hot (ie must have had some current/short or something running though) the next afternoon, a full 25hrs later.

While I was inside with the VAG-COM yesterday I lost all power and now no door locks, nothing.

I’m hesitant to put the battery on charge and repeat or make worse?

#4

Oh… ya that’s not good. That sounds like you’ve got a short circuit somewhere. Unfortunately those aren’t always real easy to find, but based on the fact that the large-gauge wire from the battery was hot, that means it’s almost for sure one of those wires themselves that’s shorting somewhere. If it was just something small that was shorted, like a headlight wire or some such thing, that wire would fry long before your main power wires got hot.

Does anyone know the route for the Positive wire from the trunk to the engine bay? I’d give the whole thing a lookover, it sounds like maybe the wire insulation is touching (or very close to touching) part of the car chassis.

#5

I’m not an expert by any means by the way, just trying to give you some ideas while we wait for the cavalry to see this thread. Unfortunately I don’t have my car right now so I don’t have a way to see what you’re talking about with my own eyes, can you post a picture of the part that was hot?

#6

That’s the battery control module and the bolt attaching the negative cable shows some signs of arcing damage. The cable was hot and the bolt hotter still.

I’m wondering if they damaged the bolt clamping the charging station to it to boost it and get it started, which in turn created a weak connection from the cable to the BCU and it’s heating up with high current passing as the system attempts to recharge the battery?

I suspect there may be a short elsewhere.

Here’s the log from yesterdays VAG-COM, address 61 near the bottom shows the battery regulator and as it is reporting I’m thinking it’s actually OK?:

Address 61: Battery Regul. Labels: 4F0-910-181.lbl
Part No SW: 4F0 910 181 E HW: 4F0 915 181 A
Component: J0644 BEM H12 0590
Revision: 00000000 Serial number: 00000000076191
Shop #: WSC 22164 444 69314
VCID: 23459275E279722643-8076

Subsystem 1 - Part No: 4F0 915 105 D
Component: von VA0 3221298181
Coding: 344630393135313035442056413033323231323938313831
Shop #: WSC 23890 444 11078

5 Faults Found:
02272 - Quiescent Current Stage 1
000 - - - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 7
Fault Frequency: 255
Reset counter: 255
Mileage: 212928 km
Time Indication: 0
Date: 2006.03.15
Time: 12:23:22

02273 - Quiescent Current Stage 2
000 - - - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 7
Fault Frequency: 197
Reset counter: 255
Mileage: 212928 km
Time Indication: 0
Date: 2006.03.15
Time: 12:26:32

02276 - Quiescent Current Stage 5
000 - - - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 7
Fault Frequency: 2
Reset counter: 255
Mileage: 214043 km
Time Indication: 0
Date: 2016.07.10
Time: 22:02:29

02277 - Quiescent Current Stage 6
000 - - - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 7
Fault Frequency: 1
Reset counter: 255
Mileage: 214043 km
Time Indication: 0
Date: 2016.07.12
Time: 12:53:57

00532 - Supply Voltage B+
001 - Upper Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 3
Fault Frequency: 1
Reset counter: 249
Mileage: 213820 km
Time Indication: 0
Date: 2006.04.23
Time: 18:54:24

#7

leec welcome to the site. Lots of very smart very helpful guys on here so always feel free to post up questions.

Before I say too much on the battery as it could be a few different things maybe take a quick photo and post it up for us to get an idea on if you even have the right wire coming off the battery and they didnt change out the wire.

click on this link…you can post all your pictures to the site. It helps you and it helps others in the future so that no picrues get lost or deleted if they take up too much spacer elsewhere.

http://audirevolution.net/image_uploader.php

As for the missifes. Generally high rpm will be injectors so be careful there. Too many high rpm missfires will take out the cats that is expensive.

Also feel free to do a full vag com scan and post the results. You can scan the entire car and all the modules. That will also give you a good idea on whats going on.

You can log the battery voltage but if the cable is hot to the toutch thats bad that says there is too much draw going through the wire. It could be where the wire is grounded on the body or on the battery. Sounds like a new battery and cleaning off the old terminals wouldnt be a bad idea.