grounding point

Seems like the few issues i am having might related to a ground that may have been disconnected. Its labelled as EC in the EWD. Anybody has any idea how to get to it? Is it under the car by the transmission ?

Hi Everyone, I had been using the grounding point of the nav computer for an aftermarket amp which I just removed yesterday. After reinstalling the bolt, I have functionally lost all audio in the car... When the sound is on, it will clip out constantly unless at a low volume. Running front...