WARNING: This page is about a different car, the 2013 Honda Fit and 2012 Honda Fit. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Audio System Circuit Diagram - Without Navigation (1 Of 2)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig 2: Audio System Circuit Diagram - Without Navigation (2 Of 2)