Great White

I have a 2004 TT convertible with 3.2l. Car runs and drives well but I cannot get communication at diagnostic port. I have power and ground to port but fail to link and know the scanner is good. I also notice there is no illumination of check engine light at all when key is first on. I have disconnected many of the modules including the Comfort control module and am down to the haldex controller which will be next as weather allows. I have checked all fuses and they are fine. I know there are some relays under the knee panel but am unsure if any of those could cause the issue I am having. Am wondering if anyone can steer me in the right direction?