2004 audi a-4 where is the engine ground wire?

There should be a ground wire from the engine to the body, from engine to the frame. Follow the neg. cable from the battery, That should be tied into the frame to engine or engine to frame.

Hi I have a 1998 audi a4 1.8t cuattro electrical problem both gas electic motor and horn do not work at the same time this happen, i checked the electric motor relay and replased it but no luck your help will be very appresiated than you.