Gearbox etc...

[Shoppinit]

Mmm. MRC know what they are doing. You could just be unlucky.

You can find the TCU on ebay / ebay.de sometimes. They used to be quite cheap.

[blm70]

Mmm. MRC know what they are doing.

That's what I thought too.

You could just be unlucky.

That would make a change...

You can find the TCU on ebay / ebay.de sometimes. They used to be quite cheap.

Was having a look earlier and found this brand new one from America-land which is quite a saving over UK stealer prices.

Do you know what the specific part number is as there seem to be loads of VAG TCUs for sale ranging from a few quid up to the one above?

Thanks.

[Shoppinit]

Part number is 4B0927156FB, so it's the right one BUT I seem to remember there being a different TCU in the USA models though. Weird that it would have the same part number.

Plenty on ebay.de. For example:

http://www.ebay.de/itm/Audi-RS6-Plus-4B ... 27f85fd020

That's £360. Feck me, they used to go for £100. I guess that's increasingly rare and exotic cars for you though.

Having said that, if you wait for a week or so until Greece implodes then you might find it's closer to £100.

Or, and I would try this first... I would get MRC to re-do whatever they did to the TCU to map it. IIRC it's a solder on chip rather than reflash, so it might be that replacing it (or reflashing) will fix it.

IF that doesn't work, remove the add-on chip and get Audi to reflash it back to original.

If that doesn't work then reflow the solder on the TCU. Sounds silly, but I fixed an S8 ECU that way. And they ain't cheap either.

[Shoppinit]

Or is there anyone local that can let you try their TCU in your car? It's a very easy swap.

[blm70]

Thanks for all the advice

Out of interest, where is the TCU located? I thought it was under the passenger floor, but if as you say it's an easy swap I'm assuming it's easy to get at...

And wouldn't buying a used TCM be a lottery?

[Shoppinit]

Yeah, it's under the carpet. Just remove the sill trim and the front a-pillar kick plate trim and you can lift the carpet up enough to get into the box.

OK, maybe it's not *very* easy but it's still pretty easy.

TCU don't go wrong often. I think the risk of getting a duff one is fairly low. Still, ebay is ebay...

[blm70]

Just stumbled across this rebuilt service http://www.ecutesting.com/audi_a4_a6_mu ... arbox.html

The link describes exactly the problem I'm having and it's the cheapest option so far, even once vat is added. Lifetime warranty sounds good too!

I have now also requested quotes from half a dozen ECU repairers including BBA Reman who are just down the road from me...

[blm70]

Update:

JT Automatics have now confirmed the TCU is definitely faulty, codes as below:

P0741-Torque converter clutch stuck off / no power transferred;

P1748-ECU checksum error.

They advised me not to bother sending it away as apart from re-soldering dry joints or basic components, the units were not repairable i.e. I could send it away, pay £200 + vat (the going rate), receive it back a week later 'repaired' to find it still doesn't work. This could be down to a missing or corrupt part of the programming that can't be fixed. Then I'd have an almost impossible job trying to prove they hadn't fixed it...

They had never come across a reliably repaired TCU either.

So the next option (and one they were in favour of) was to purchase a used working one from eBay. This is the one I've just bought and the seller did confirm I could send it back for a full refund (minus postage) if I changed my mind.

If I'm lucky this will fix the problem completely, or the TCU checksum error will be cleared but there will still be a gearbox problem...

Apparently, earlier models of this car had the TCU bolted to a piece of wood

Interestingly, they did say that in their experience torque converter issues were rare and only really seen in certain Range Rover models that use a similar transmission but are much heavier cars.

Still, until the TCU issue is resolved, they can't address any potential gearbox problems.

[Shoppinit]

Let's hope that sorts you out then.

Odd they would say that TC issues are rare. It's one of the most common failure modes on the RS6. Maybe they haven't seen a lot of RS6 boxes.

[Mɐʇʇ]

What Shop said - in my (limited) experience, the TC letting go is often the first thing to fail on these - and then all the crap from it cycles round and chews up the rest of the box.

Cheeky request - can I have your broken TCU?

Final point - don't forget to reset all DTCs once the new TCU is in. e.g. once a TC error is logged it'll often not even attempt to engage it from then on, so you'll not see if its improved or not.

[blm70]

Let's hope that sorts you out then.

Fingers crossed...

Odd they would say that TC issues are rare. It's one of the most common failure modes on the RS6. Maybe they haven't seen a lot of RS6 boxes.

That's what I thought too, perhaps you're right.

[blm70]

What Shop said - in my (limited) experience, the TC letting go is often the first thing to fail on these - and then all the crap from it cycles round and chews up the rest of the box.

Yep, I've read similar horror stories.

Cheeky request - can I have your broken TCU?

Let's see what happens...

Final point - don't forget to reset all DTCs once the new TCU is in. e.g. once a TC error is logged it'll often not even attempt to engage it from then on, so you'll not see if its improved or not.

Got it, thanks Matt.

[Mr V10]

If that's the case then shame on AMD.

Not at all.

They're a business, buying/sourcing a product/service and selling it for a greater cost, thus making a profit. Just like the last supermarket you shopped at.

[blm70]

Good point, although if the 'box does need repairing then at least I will have cut out (some of) the middle men.

[Special K C5]

Mine had a MRC stage 1+ and i needed a new TCU which i relpaced(while advertised for sale ) and only waited for a couple of days for the part to arrive and then be fitted. My box was fine and still is to this day as my mate bought the car and has no problems with it since.