I have seen many threads on here and AW on what it takes to convert the normal automatic in a 97 1.8t to tiptronic. It is very simple and can be done in a few short hours with very little experience and the right tools. Believe it or not I paid under $200 for everything
******This will only work on a 1.8T engine not the 2.8********
First I started with Pauls page HERE
The only difference between his install in the A8 and the A4 is the A4 is not wired for tiptronic already at the tcm.
BEFORE YOU START, I DO NOT EXCEPT AND RESPONSIBILITY FOR ANYTHING THAT YOU DO TO YOURSELF OR YOUR CAR AND DO THIS UNDERSTAND YOU ARE DOING THIS AT YOUR OWN RISK!!!!
What you need:
Tiptronic shifter assembly (ebay)
TCM out of a 98,99,or 99.5 1.8T (2000 didn't work for me)
Prybar or flathead screw driver
Philips head screw driver
Network cable or anything with 3 thin wires (different colors)
Tiny metal connectors
The How To:
First thing is remove the center console, if you do not know how to do this there is a how to on AW.
Remove the shifter cover and shifter knob.
disconnect the brown 4 pin connector and the 2 pin neutral connector.
Remove the 4 8mm nuts that surround the shifter
Remove the 8mm bolt that secures the neutral cable and remove the neutral cable from the shifter
push down the 4 tabs on the shifter and it should drop a little but not completely
For the next part...MAKE SURE THE CAR IS VERY COOL TO THE TOUCH!!!!!!!
Now to get under the car, this can be done with a pair of ramps or by jacking up both sides. Make sure you have your parking break on.
Once underneath the car you will see that the drive axle is blocking the shifter assembly from coming out, remove all 6 torx and move the axle to the side.
now you should be only stopped the shifter cable itself which just pops off with a long screwdriver
Ok now install your new one and reassemble the axle and make sure it is loaded with grease and you should replace the gasket..I didn't but I'm sure you should
Now back in the cabin you want to remove the passenger side kick panel which should be one screw, then pry up passenger side floor molding
Now lift up the carpet in front of the passenger seat and you will see a black box. lift that out, there will be plenty of slack to pull the whole unit out to work on.
Open the box by depressing the two tabs and you should see your TCM, remove that
unplug the tcm and get rid of that tcm.
Now you will open up the harness by removing the philips head screw and the metal banding around the side of the harness
Now you can remove the plastic from around the wiring harness
now you will need your tiny connectors, connect 3 of them to wires atleast 2 feet long.
Now you need to put the connectors in pin 13, 47, and 48. The pin numbers are on the tcm so use that to figure out which one it is on the harness (make not of what color is in what pin)
Put your harness back together and plug in the new TCM...I used 8D0 427 156 BN which is a 99.5 1.8TQ
Run the 3 wires underneath the carpet up to the shifter
Cut the 4 pin connector and the 2 pin connector on the car
If your tiptronic still has the connector harness on it that needs to also be cut
now you should have a total of 8 wires in the car and 7 on the shifter.
Now you need to connect the the neutral wires from the tip to the same colors in the car
connect the other like colors, I believe that there is 2 grey and blue colors and I had them flipped before one goes to teh neutral switch and the other is power for the led's in the shifter, if you put a meter you should get 12volts only when the lights are on for the one connected to the LED's (obviously)
Now you should have 3 wires that need to be connected, One is for tip engage and the other 2 are for shift up and shift down.
13 = Violet/Yellow
46 = Violet/Red
47 = Violet/Blue
Now just turn on the car and go for a drive, if you move over into tip you may or maynot see the 54321 (I don't on my cluster) but you should still see be able to shift up or down
All set, enjoy having tiptronic and try not to think about how you still want a 5speed