Pardon my ignorance, I have done a bunch of searching but haven't found a concreate answer.
I have a 2001 TT Roadster and noticed that in the back right compartment in the well, there is a 20 pin serial cable. I assume it is there for the optional factory nav unit. Is this correct? If so, all roadsters are pre wired for factory nav? I looked at some pics of the unit itself and didn't see any cables that looked like a normal 20 pin serial, so I am confused. Thanks!

 

There are a lot of compartments are you talking about inside the cab, or in the trunk?

 

Inside the cab, in the well where the top folds into. There are 2 covers that lift up. This plug is under the cover on the passenger side. Thanks.

 

Not sure about the pass. side the nav hookup is on the driver's side, but it would be where the top folds up.
Check this out for a better understanding, just register to see the image. Clicky!

 

Thanks for the link, I've seen that pic but it doesn't really help me. I'm thinking that this compartment and serial cable are where the actual navigation drive (number 3 in your pic link) goes (there is also a bracket in there to hold something). But I'm still confused about the 20 pin serial as the pics of the nav drives don't seem to have a serial connection. Surely someone else has noticed an extra serial cable that doesn't do anything hidden in their car.

 

The only other thing I can think of is the OBD port... but that's usually under the headlight switch.
Unless roadsters are backwards like that...

 

Upon further inspection, it is a 25 pin, not 20, female serial cable. There is also a wire with a coax connetor on it. I assume this is the gps antenna. I'm curious if all '01 roadsters are pre wired like this, and if so, can a nav unit just be dropped in there and the controls added to the center console?

 

*bump*

I still haven't figured this one out. Possibly something for the in car phone system? I've looked through the audi repair manual and still can't find an answer.....

 

Since 90% of the people here are coupe guys...I think he's talking about the serial cable that (on a coupe) would be in the little door in the left wall of the hatch that you'd use to access headlight wiring. I saw it there while doing an Audio install, was kinda curious what it was for myself.

Factory nav adds a little console in the middle next to the ebrake (where your unlock/lock button and top/glass up/down button are) so I don't think that they're entirely "pre wired."

 

The navigation unit is on the passenger side for the roadster.
I've never taken mine out so I can't verify the connection and I don't have my bentley manual with me here.