2009-11 Models

Remove the front grille cover (see FRONT GRILLE COVER REPLACEMENT ).
Disconnect the 1P connector (A) from the horn (B).

Fig 1: Identifying 1P Connector From Horn
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Connect the terminal (A) to the battery power, and the bracket (B) to body ground.

Fig 2: Identifying Bracket To Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
If the horn does not sound, replace it.