We have a 1998 Audi A6 Quatro, it has 160,000 miles on it.
Problem: When the car is started and put into drive - it seems like it goes into gear, but doesn't. The car will free-wheel, but not kick into gear. It can be forced into "default" mode, and the transmission will go into 4th and then take off, but only in 4th.
Reverse is no problem.
Cannot find information to help troubleshoot this problem.
Question: Is the shifting of gears electronic, mechanical or both?
Could a bad wiring connection cause this problem?

Continuing:

We have been doing an is / is not process on the car. We haven't quite figured out what the problem is but we feel we are getting close. We do not feel it is an oil change issues as everyone seems to suggest. We believe it is an electronic issue with the transmission control module, solonoid or relay.
The thought behind this is, when we can get the car up to 5 miles an hour (rolling it down a hill), in tiptronic mode, the car will smoothly shift into first gear, and from there we can drive the car and shift from 1st - 5th and back without incident. When in 1st - it will stay locked in even when stopped. BUT, if we stop the car in 2nd, we are back to square one and the car will not shift into 1st.
Also, with the same start of rolling it down the hill, we can get it into "D" drive mode, and it is fine while in motion, but will go back to doing nothing when we come to a complete stop.


Well, after these posts on another forum, I sure hope our problem is electrical, since we surrendered to the "change the oil" gods, which were fickle and replied - go fish.

We've changed the transmission fluid, and still didn't correct the problem. We had issues with the "check engine" light, and among all of our tests, we found the battery needed to be replaced. We swapped it out with another one, and found the small wire on the plus side of the battery was corroded badly. We replaced the end, and reattached it. The check engine light hasn't come back on.

We found if you remove one of the wires on the air cleaner intake, it will make the transmission (in our case) go into fail safe mode. You can drive the car in 4th gear only - without having to making the trip in reverse.

This has become a major source of frustration, but we're still in the search and destroy mission to see if we can get this fixed without the major $$$ a new transmission would require or taking it into a shop to have someone say "it's only a loose wire".

We were able to do the transmission oil check and fluid change ourselves, but realize not everyone has the ability or the tools required to do so. We will continue to post our findings to assist others if this information is helpful as we have looked long and hard to find some sort of solution with little help and few results.

It seems shops have never heard of our problem, though through another site we realize it seems to occur and not an isolated issue.

If anyone has information that will help - we would greatly appreciate it.

 

Perhaps you did not refill and check the ATF level per the BentleyPublishers.com Audi shop manual DVD. Diving with the incorrect fluid level may not be good for your transmission.
You may get automatic transmission information from www.atsg.com .

 

Sure sounds like a low fluid situation.. could be the pump too. Electronic wise, look at the speed sensor.