1995 A8 4.2 quattro problems after 8 months storage
 

I have bought an audi a8 that supposedly has been stored for 8 months because the people that owned the car liked it to much to sell it. But now the building they stored it in is no longer available and they had no place for it to go and it got up for sale. That is kind of the story i got(dont know if its true)
But the problems are that the car had a dead battery(wich is perfectly normal in 8 months) But after replacing the battery the car is having the transmission in limp mode, and when trying to connect to it it dosnt work. The engine ecu said something like no communication with tcu(dont know code nr anymore). Also the rev counter and speedo dont work, so this might also be on the same problem. According to the previous owner it was driving fine when they stored it, and that seems plausible because it was not too long after the yearly inspection.

So has anyone had something like this happen? Can this be caused by the dead battery?

Things i have tried: disconnect the tcu and reconnect. Connector didnt seem corroded and since it was dry stored there was no water in the box either. And i tryed resetting everything by auto scanning and reset, but it didnt change anything.

Other then the tcu and the cluster problem she runs fine and drives ok, but cant really tell how wel because limp mode probably means 3th gear only(atleast that is how it feels)

Try cleaning the cluster and ECU connections. Failing that, try disconnecting other major modules such as ABS. Sometimes one unrelated-sounding module will cause communication issues for the others. If you can do a full scan with VCDS and post the results that'd also be helpful.

Look for mouse-chewed wires or mouse piss-corroded connections?

I have not done the vagcom scan yet because i didnt want to take the laptop with me, so i brought the launch with me wich in the past has shown exactly the same as the (original) vagcom we have. And it showed no communication with the tcu only. But once it arrives here ill try the vagcom and see if that manages to find some other things.
What i have been thinking about is that it might indeed have a controller that is faulty and that gets the canbus network all screwed up. I dont know if that is common on this model? And i have read on here that a lot of people say disconnect the abs module. Is the abs module 1 that fails often? Or is that just a random guess?

finally had time to work on it again. Tryed a few things but got absolutely no communications with the transmission controller. So i pulled it out of the car, and i found my transmission problem. Its dry in there now, even with the lots of rain we had the last week. But you can clearly see the corrosion marks on the outside allready. So i openend her up and the board has some nice white flakes on the lower part of it, so it has been submerged been submerged in about 1 inch of water i estimate. So i think i wont be able to fix it, but if i could find a scematic of the controller i might give it a try.

But the instrument cluster also dosnt move. The rev counter and speedo stay in the corner as well. Can anyone tell me where it gets its signal from?

stored mine for 5.5 months,didnt want to run without fresh fuel and new battery,maybe the old one would work if i recharched it but it was 4 years old and i wanted a new one anyway.

that is why i allready tried 2 batterys on it. I had strange problems before with cars all because the battery didnt meet the specs anymore. So sometimes it might start but it still causes strange problems.

But as far as i can tell on this 1 now it seems like the transmission controller has been in water because of the common water in the electrical box problem. So im going to try and borrow a trans controller from someone i know. Atleast i think he still has an a8 in his storage, and if so i can probably try it. Dont wat to buy parts to then find out that wasnt the problem.

this happened to me on 2014 mks lincoln,dead rat on the bottom of the belly pan,ate my injector wires,i think newer car have eco friendly edible wire sleeves or how ever you call that.

Sounds like car had problems before it was stored and the owners did not tell you?

could be, but the price was so good that even if it is broken it will be worth the money and some more in just parts. Essentially i just bought the engine, and the rest of the car came free because when i got there i found all these problems and told him well its a piece of ****, named all the things wrong with it and said ill take it from you for prettymuch scrap money, but only because i am here now. And after a while he decided he wanted it gone.