mr.allan.brown@googlemail.com

My 2001 S8 has gone from having no gear issues to stuggling to change twice this morning then going into limp mode (all gear lights highlighted on dash) and selecting 5th only. I will be getting it checked out in the morning but hoped someone may have some idea of the problem and what it may cost to rectify. Thanks in advance

audistefan

did you get water under the carpet and do you have a sunroof is so look under ther and you will find out why.let me know please so i can help you very much with this

silverd2

D2 A8/S8 does not have a TCM (or any related wiring) under the carpet. That is only an issue on some other Audi's and VW's.

The D2 TCM is in the sealed electronics box under the hood (bonnet) in the fresh air plenum. In some cases the E-box can get water intrusion, due to clogged rainwater drain in the plenum. It's easy to unbolt the top of the box to check for water intrusion and/or corrosion on the connections.

At the very least, you need to have a Vagcom diagnostic to check for trouble codes...plus check ATF level, look for ATF leaks under the car and any oil around the gear box's electrical connections.

IF the trans needs a rebuild or rebuilt trans swap (worst case scenario), that can cost $3500-5000.

Kolya Milos

On my 1997 A8 same thing happened, but the lights stay on, and it would not start at all.
I found 20A fuse in the box under the hood ( where TCU is) which was blown.
The code was P0730 9 (dreaded), P0703, P1857 and P1850.

It starts now, but I do not know for how long.

I have to find out: Why did the fuse blow in the first place???

Will let you know.

mr.allan.brown@googlemail.com

Just to give you an update. I have had the car into a specialist and apparently one of the drums in the gearboox has been destroyed taking a number of components with it. When ringing around for quotes I was told on a number of occasions that this is a common failure for this greabox and at 164k miles I had done quite well. I have agreed (with sadness) to a £2500 rebuild. One of the reasons for the expense is the type of transmission fliuid they will use to refill. There are 2 types one good for 50k miles the other for life. I have opted for the long term one

silverd2

£2500 ($3900) is not surprising, within range, for the rebuild...esp if that includes all labor of re-installation. But the cost has very little to do with the fluid >>>

- - "There are 2 types one good for 50k miles the other for life. I have opted for the long term one" - -

There is no such thing as lifetime fluid...that was a "white lie" slogan invented in an Audi boardroom to justify the cost of their OEM fluid, at about around $25 per liter...about $200-250 of your cost.

The only truth in the "lifetime" claim is that you can indeed leave it in your trans (just like ANY brand) until the trans dies

rhann

I have a limping 2000 A8 which is said to be the TCU. I have one on order and will replace when it arrives. I'd be interested to know about the 20A fuse and where you found that. If you can provide details, it could be a source as well if not this time, then the next tranny issue I encounter.